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Digitized  by  the  Internet  Archive 

in  2011  with  funding  from 

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THE  A  B  C  OF  VACUUM  TUBES 
IN  RADIO   RECEPTION 


AN   ELEMENTARY   AND    PRACTICAL   BOOK   ON    THE- 
THEORY    AND    OPERATION    OF    VACUUM    TUBES 
AS  DETECTORS  AND  AMPLIFIERS.     EXPLAINS 
NON-MATHEMATICALLY     THE     FUNDA- 
MENTAL PRINCIPLES   UPON   WHICH 
ALL    VACUUM     TUBE    CIRCUITS 
ARE  BASED 

Includes 

PRACTICAL  CIRCUITS   AND   PRACTICAL  QUESTIONS 

AND   ANSWERS.      IT   IS    WRITTEN    ESPECIALLY 

FOR  THE  BEGINNER.    ALL  ELECTRICAL  AND 

RADIO   TERMS  ARE  FULLY  EXPLAINED 

E.  H.  LEWIS  u 

Assoc.    I.R.E.,  Radio  Instructor, 
East   Side  Y.   M.   C.   A.,   New  York  City. 


FULLY  ILLUSTRATED 


New  York 

THE 

NORMAN 

W.  HENLEY 

PUBLISHING 

CO. 

2 

West  45th   Street 

1922 

Copyrighted,  1922 

BY 

The  Norman  W.   Henley  Publishing  Co. 


427^7 


PRINTED   IN    U.    S.   A. 


PREFACE 

The  inauguration  of  radio-telephone  broadcasting  has 
quickly  aroused  an  enormous  general  interest  in  radio  reception 
of  speech  and  music.  The  possibilities  of  this  new  method  of 
broadcasting  information  of  general  interest  and  entertainment 
can  hardly  be  estimated.  The  method  is  revolutionary  and 
has  been  aptly  compared  to  the  invention  of  the  printing  press 
in  this  respect. 

Vacuum  tubes  make  possible  the  reception  of  radio-telephone 
speech  and  music  and  radio-telegraph  signals  with  a  degree  of 
satisfaction  not  approached  by  prior  devices. 

The  vacuum  tube  appears  to  the  layman  as  a  complicated 
form  of  incandescent  electric  lamp  which  operates  in  a  very 
mysterious  manner.  In  writing  this  little  book  the  author  has 
endeavored  to  overcome  this  impression  and  to  clearly  set  forth 
the  elementary  principles  of  theory  and  operation.  It  is 
assumed  that  the  reader  has  no  knowledge  of  radio  and  very 
little,  if  any,  of  electricity.  Mathematics  has  been  especially 
avoided  in  the  treatment  of  the  subject  and  no  technical  terms 
are  used  without  their  meaning  being  made  clear. 

The  functioning  of  the  "lamps"  is  fascinating  to  a  great 
many  people  and  the  author  hopes  that  the  desire  for  elementary 
information  regarding  it  will  be  fulfilled  in  the  text.  No 
attempt  has  been  made  to  set  forth  all  the  possible  circuit 
arrangements  but  those  shown  may  serve  as  suggestions  to 
experimenters  who  desire  to  evolve  their  own  circuits.  The 
practical  questions  and  answers,  it  is  hoped,  may  be  of  value 
to  those  who  are  contemplating  the  installation  of  receiving 


PREFACE 

equipment  or  who  are  getting  unsatisfactory  results  because 
of  insufficient  information. 

Suggestions  regarding  improvement  of  the  material  pre- 
sented and  the  manner  of  presentation  will  be  gratefully 
received  from  readers. 

April,  1922.  The  Author. 


CONTENTS 

PAGE 

CHAPTER  I 

Introductory 

Electric   current — Electrical    pressure    or    Electromotive    force — Resist- 
ance— Direct  current — Alternating   current — Frequency — Inductance 
.  — Capacitance — Resonance — Oscillations — The     Reception     of     sig- 
nals— Wave   length — Tuning  the   receiving   antenna — The   Antenna 
as  a  complete  circuit 15 

CHAPTER  II 

The  Vacuum  Tube  as  a  Rectifier  and  Relay  Without  Moving 

Parts 

Tube  construction — The  Edison  Effect — Electron  emission  from  a 
heated  filament — Dependence  of  plate  current  upon  plate  potential — 
Dependence  of  plate  current  upon  filament  current — Effect  of  grid 
potential  upon  plate  current — Relay  action — Rectification   ...     38 

CHAPTER  III 
The  Vacuum  Tube  Detector 

The  telephone  receiver — Simple  detection — Detection  with  grid  con- 
denser— Effect  of  gas  in  a  detector  tube — Heterodyne  action  or  the 
production   of   beats 59 

CHAPTER  IV 
The  Vacuum  Tube  Amplifier 

General  characteristics — Audio  frequency  amplification — Radio  fre- 
quency amplification — Radio  frequency  regenerative  amplification — 
Autodyne   production    of    beats 76 

CHAPTER  V 
Practical  Circuits  and  Their  Operation 

Methods  of  coupling — The  variometer — Inter  electrode  tube  capaci- 
tance— Wave  length,  Frequency  and  Resonance — Circuits  and  expla- 
nations of  their  arrangement  and  operation     ......     90 


CONTENTS 

CHAPTER  VI 
Voice  Distortion 

PAGE 

Amplifier   transformers — Normal   grid   potential — Too   great   regenera- 
tion— Telephone    receiver       .        . .    in 

CHAPTER  VII 
Practical  Questions  and  Answers 
Practical    Questions    and   Answers    .       .........   116 


~  List  of  Symbols  ~ 

Battery — 1||  |  |h- 

Direct  Current  Dynamo  ---       Bh  M  ^B         ca 

Alternating  \  ^-.  re- 
current         f Xy~      or       _JQ) 

Generator    )  ^— ^  v — 

Fixed  Capacitance  "  T" 

(Condenser  ) 

Variable  Capacitance lb* 

f  l^br:  Condenser)  /\\ 

4 

/vW   Inductance _..^^7ffiff5ff\„ 

(Air  Core  Coil)  VUVVVU 

Variable  Inductance _y"^W$x_.  ^r  _i^^p_ 

(Air Core  Coil)  y^  a 

Variometer  (  Variable  Inductance)  — 

Fixed  Co  up  ling  of  Co  Us        — \JHlfifiil/~~ 

(Fixed  Inductive  Coupling)  ^TT\Kf^\^ 

Variable   Coupling  of  Coils 

t  ,  "IS 

Transtormer— gj 

Iron  Core  Inductance 
(  or  Reactance   Coil ) 


-List    of    Symbols- 


Antenna 

Ground 

Wire  Connections 


V 


or 


V —^ 


or 


No  Connections   of  Wires 
Fixed    Res  is  tctnce 


Variable   Resistance 


Vacuum   Tube  — 


Telephone    Receivers 


Voltmeter  -  •■ 


Ammeter 


Galvanometer 


— vww— 


GALVO. 


Crystal  Detector 


*$ 

2J 


CHAPTER    I 


INTRODUCTORY 


Electric  current — Electrical  pressure  or  Electromotive  force — Re- 
sistance— Direct  current — Alternating  current — Frequency — Inductance — 
Capacitance — Resonance — Oscillations — The  reception  of  signals — Wave 
length — Tuning  the  receiving  antenna — The  antenna  as  a  complete  circuit. 

Before  taking  up  the  subject  of  vacuum  tubes  a  brief  out- 
line of  the  most  common  electrical  and  radio  phenomena 
together  with  the  explanation  of  common  electrical  terms  will 
be  given.  It  is  understood  that  for  some  this  may  be  a 
review  of  knowledge  previously  gained.  For  others  it  may, 
however,  serve  to  fix  some  very  vague  understandings  and 
some  familiarity  with  these  fundamental  facts  is  necessary  in 
order  to  comprehend  that  which  follows. 


Electrical  Current 

It  is  very  commonly  known  that  a  battery  and  a  dynamo 
furnish  what  is  called  a  "current  of  electricity"  and  that  the 
electrical  current  will  not  flow  unless  a  path  is  provided  for 
it.  The  path  is  called  the  "electrical  circuit"  or  simply  the 
"circuit."  For  example,  if  it  is  desired  to  ring  a  door-bell 
it  is  necessary  to  connect  the  bell  to  a  battery  by  means  of 
insulated  wires  and  if  the  path,  or  circuit,  is  broken  at  any 
point  the  bell  will  not  ring.  A  push  button  may  be  used  to 
keep  the  circuit  broken  until  the  button  is  pressed,  whereupon 
an  electric  current  flows  through  the  circuit  and  the  bell  rings. 

IS 


i6 


A  B  C  OF  VACUUM  TUBES 


Fig.  I  represents  such  a  circuit  which  may  be  closed  at  will 
by  pushing  the  button.  Since  no  electricity  flows  when  the 
circuit  is  open  we  may  assume  that  it  flows  in  all  parts  of 
the  circuit  when  it  is  closed.  Thus,  if  the  current  flows  from 
the  battery  at  "A"  it  must  return  to  the  battery  at  "B."  The 
terminal  of  the  battery  from  which  the  current  flows  is  called 


\Push  Button 


Contacts 


Positive 
Terminal-' 


B 


& 


Bell 


-  Negative 

Terminal 


Battery 
Fig.  i — Simple  electrical   path   or   circuit. 


the  "positive  terminal  and  the  other  the  "negative"  terminal. 

To  illustrate  the  flow  of  current,  a  closed  circuit  of  pipe 

may  be  used.     A  pump  is  located  at  "A"  in  Fig.  2  and  the 


Fig.  2 — Water   analogy  of    simple   electrical   circuit. 

pipe  is  considered  to  be  full  of  water.  When  the  pump  is 
operated  the  water  will  be  forced  to  flow,  let  us  say,  in  the 
direction  of  the  arrow.  It  flows  from  the  pump  through  the 
pipe  and  returns  to  the  pump  and  the  same  amount  of  water 
which  leaves  the  pump  in  one  second  of  time  will  return  to 


INTRODUCTORY  17 

it  in  the  same  length  of  time.  In  other  words,  there  is  a 
continuous  flow  of  water  until  the  pump  stops.  This  corre- 
sponds to  the  electrical  circuit  and  it  may  very  easily  be 
proven  that  the  current  is  no  stronger  in  one  part  than  it  is 
in  any  other  part  of  the  circuit. 

We  may  measure  the  current  or  rate  of  flow  of  the  water 
in  gallons  per  second.  That  is,  if  there  is  one  gallon  flowing 
in  one  second  past  any  given  point  in  the  pipe  the  rate  of  flow 
is  one  gallon  per  second.  The  current  or  rate  of  flow  of 
electricity  also  may  be  measured  and  the  unit  is  called  the 
"ampere."  The  rate  of  flow  of  electric  current  is  sometimes 
referred  to  as  its  "strength"  and  if  the  current  strength  is 
one  ampere  its  rate  of  flow  is  one  ampere,  a  certain  fixed 
quantity  of  electricity  per  second. 

It  must  not  be  assumed  that  electricity  is  actually  a  fluid 
like  water.     It  is  not.     No  one  knows  just  what  electricity  is 
but  its  effects  may  be  noted  and  its  "flow"  may  be  compared 
in  many  respects  to  that  of  water, 
i 

Electrical  Pressure  or  Electro-Motive  Force 

Electrical  pressure  is  referred  to  as  "electro-motive  force" 
since  in  order  to  create  a  current  of  electricity  it  is  necessary 
to  provide  some  force  to  make  it  flow.  In  the  case  of  the  pipe 
full  of  water  the  pump  must  exert  a  force  or  pressure  upon 
the  water  to  push  it  through  the  pipe.  In  the  case  of  the  elec- 
trical circuit  in  Fig.  1  the  battery  furnishes  the  electrical  pres- 
sure. Neither  water  nor  electricity  can  flow  unless  a  pressure 
is  provided.  If  we  wish  either  the  water  or  the  electric  cur- 
rent to  flow  faster  (at  an  increased  rate)  the  pressure  applied 
to  it  must  be  increased. 

Water  pressure  may  be  measured  in  pounds  per  square  inch 


18  A  B  C  OF  VACUUM  TUBES 

but  electrical  pressure  or  electro-motive  force  is  measured  in 
volts.  Sometimes  electrical  pressure  is  referred  to  as  'Volt- 
age." E.  M.  F.  is  a  convenient  abbreviation  to  use  for  the 
long  expression  "electro-motive  force"  and  it  will  be  used 
hereafter  in  this  text. 


Resistance 

When  water  flows  through  a  pipe  there  is  always  a  certain 
amount  of  friction  between  the  water  and  the  pipe.  This  hin- 
ders the  flow  of  the  water,  that  is,  reduces  the  rate  at  which 
the  water  current  flows.  And  the  reduction  in  rate  of  flow 
depends  directly  upon  the  increase  of  the  friction.  Likewise 
there  is  friction  present  in  the  path  of  the  electric  current 
which  acts  as  a  "resistance"  to  the  current  flow.  If  the  pres- 
sure or  E.  M.  F.  is  kept  constant  the  rate  of  current  flow 
(current  strength)  increases  as  the  resistance  is  decreased  and 
vice  versa.  If,  however,  the  resistance  is  kept  constant  it  is 
natural  to  expect  the  current  (rate  of  flow)  of  the  electricity 
to  increase  with  an  increase  of  E.  M.  F.  and  vice  versa.  The 
current  thus  depends  upon  both  the  resistance  and  the  E.  M.  F. 

The  unit  of  electrical  resistance  is  called  the  "ohm"  and 
if  the  resistance  of  a  circuit  is  one  ohm,  one  ampere  of  cur- 
rent will  flow  if  the  E.  M.  F.  is  one  volt.  This  relation 
between  current,  E.  M.  F.  and  resistance  is  called  "Ohm's 
Law"  and  is  the  first  fundamental  law  of  electrical  circuits. 

Direct  Current 

If  the  E.  M.  F.  applied  in  a  circuit  is  steady  and  only  acts 
to  force  the  current  to  flow  in  one  direction  through  a  circuit 
the  resulting  current  is  steady  and  is  called  a  "direct  current." 


INTRODUCTORY 


19 


If  the  E.  M.  F.  rises  and  falls  but  only  acts  in  one  direction 
the  resulting  current  rises  and  falls  and  is  called  a  "pulsating 
direct  current"  or  a  "pulsating  current."  Batteries  produce  a 
steady  direct  current  in  one  direction  through  a  circuit.  Many 
dynamos,  however,  produce  a  pulsating  E.  M.  F.  which  causes 
a  pulsating  current  to  flow  (in  one  direction  only)  through 
a  circuit.  The  periodical  increases  and  decreases  of  E.  M.  F. 
and  current  may  be  made  very  small,  however,  so  that  they 
are  hardly  perceptible. 


Alternating  Current 

Imagine  that  instead  of  a  battery  we  have  a  dynamic  gen- 
erator of  electrical  pressure  in  a  circuit  and  that  the  E.  M.  F. 
produced  acts  in  first  one  direction,  then  the  other,  and  that 

^  Second  of  Time 


Current  Max. 
in  Heg.  Direction 


Fig. 


3 — One  cycle  of  current  changes  and  reversals. 

per  second. 


Frequency  60  cycles 


while  acting  in  each  direction  it  increases  to  a  maximum  value 
and  decreases  to  zero.  The  current  created  will  also  change 
its  direction  of  flow  and  increase  and  decrease  in  strength 
periodically,  as  shown  in  Fig.   3.      Such  a  current  could  be 


20  A  B  C  OF  VACUUM  TUBES 

said  to  "alternate"  in  its  direction  of  flow  and  is  aptly 
called  an  "alternating  current."  These  alternations  or  rever- 
sals of  current  flow,  with  their  accompanying  increases  and 
decreases  in  rate  of  flow,  take  place  very  rapidly  and  at  per- 
fectly regular  intervals.  In  this  figure  the  current  values  or 
"rates  of  flow"  are  shown  as  increasing  and  decreasing  in 
one  direction  above  the  horizontal  line  and  increasing  and 
decreasing  in  the  opposite  direction  below  that  line.  In  order 
to  distinguish  the  directions  of  flow  from  each  other 
we  may  call  one  the  "positive"  direction  and  the  other  the 
"negative"  direction,  so  that  all  current  values  along  the  ver- 
tical line  and  above  the  horizontal  line  are  in  the  positive  direc- 
tion and  all  those  along  the  vertical  but  below  the  horizontal 
are  in  the  negative  direction.  During  the  period  of  time  rep- 
resented by  the  horizontal  line  the  current  has  increased  to  a 
maximum  value  and  decreased  to  zero  in  the  positive  direc- 
tion then  has  reversed  its  direction  and  increased  to  a  maximum 
and  decreased  to  zero  again.  In  increasing  and  decreasing, 
the  current  has  passed  through  all  values  from  zero  to  maxi- 
mum in  each  direction.  It  has  thus  gone  through  one  "cycle" 
of  current  changes  and  directions  of  flow.  As  long  as  the 
E.  M.  F.  acts,  the  current  will  continue  to  go  through  these 
changes  in  a  perfectly  regular  manner  periodically. 

Frequency 

In  the  ordinary  house  lighting  circuit,  if  it  has  alternating 
current,  the  periodical  reversals  of  current  flow  usually  take 
place  at  the  rate  of  60  cycles  per  second.  It  may  be  said  then 
that  the  "frequency"  of  the  alternating  current  is  60  cycles 
per  second. 

In  radio  work  extremely  high  frequencies,  varying  approxi- 


INTRODUCTORY 


21 


mately  between  15,000  and  2,000,000  cycles  per  second,  are 
also  used.  Such  very  high  frequencies  are  called  "radio  fre- 
quencies." It  is  not  within  the  scope  of  this  little  book  tc 
discuss  the  various  methods  of  producing  alternating  currents 
of  high  frequency  but  it  may  be  said  that  all  radio  transmitters 
do  produce  them  and  that  they  are  very  essential. 


Inductance 

Inductance,  or,  more  properly,  "self  inductance,"  is  a  prop- 
erty possessed  to  a  greater  or  lesser  extent  by  every  electrical 
circuit.  It  has  no  effect  upon  a  direct  current  but  does  have 
an  effect,  which  will  be  discusssed,  upon  an  alternating  cur- 


k- I  Cycle  of  Current J 

Fig.  4 — Effect  of  inductance  in  an  alternating  current  circuit. 

rent.  As  shown  in  Fig.  4  it  has  the  effect  of  causing  the 
current  to  rise  to  its  maximum  value  after  the  maximum  value 
of  E.  M.  F. 

The  current  is  said  to  "lag"  behind  the  E.  M.  F. 

"Reactance"  is  the  name  given  to  an  "effective"  resistance 
to  alternating  current  which  depends  directly  upon  the  value 
of  the  inductance  and  upon  the  frequency  of  the  alternations. 


22  A  B  C  OF  VACUUM  TUBES 

In  an  alternating  current  circuit,  if  we  for  the  moment  disre- 
gard the  actual  resistance,  the  average  value  of  current  decreases 
as  the  reactance  increases  providing  that  the  E.  M.  F.  has  a 
constant  average  value.  That  is,  the  reactance  has  the  effect 
of  a  resistance  although  it  is  not  true  "ohmic'  'or  actual  resist- 
ance. If  the  circuit  contains  reactance  and  ohmic  resistance, 
the  average  current  value  will  decrease  with  an  increase  in 
either  or  both  providing  again  that  the  average  E.  M.  F.  is 
constant. 

A  straight  wire  possesses  inductance  to  some  extent  and 
the  inductance  of  a  wire  increases  with  its  length.  Given  a 
certain  length  of  wire,  its  inductance  and  therefore  its  react- 
ance may  be  very  greatly  increased  by  coiling  it.  Also,  if 
more  turns  are  added  to  the  coil  or  if  an  iron  core  is  placed 
inside  of  it,  its  inductance  is  increased  and  its  reactance  as 
well. 

To  distinguish  this  type  of  reactance  from  a  type  considered 
below  we  may  call  it  "inductive  reactance."  To  sum  up,  then, 
inductive  reactance  depends  directly  upon  the  inductance  and 
frequency  of  current.  The  average  value  of  alternating  cur- 
rent in  a  circuit  varies  inversely  with  the  reactance. 
* 

Capacitance 

Capacitance,  or,  as  it  is  sometimes  called,  "capacity,"  has 
exactly  the  opposite  effect  of  inductance  upon  an  alternating 
current.  Capacitance  has  the  effect  of  causing  the  current  to 
rise  to  its  maximum  value  before  the  E.  M.  F.  The  current 
in  this  case  is  said  to  "lead"  the  E.  M.  F.,  as  is  graphically 
shown  in  Fig.  5. 

*  The   reciprocal   of   the   product   of   capacitance   and    fre- 

*  If  the  product  were  2,  the  reciprocal  would  be  l/2.     The  reciprocal  of 

3  is  1-3,  of  2x  100  it  is  ■ 1—  and  so  forth. 

2  X  100 


INTRODUCTORY  23 

quency  determines  the  value  of  a  reactance  which  in  this  case 
may  be  called  a  "capacitive  reactance."  The  capacitive  react- 
ance, however,  does  not  have  the  effect  of  a  resistance  to  the 
alternating   current  but   exactly   the    opposite.      The   average 

/  Cycle  of  Current p\ 


I  I 

^ I  Cycle  ofE.M.F. >j 

Fig-  5 — Effect  of   capacitance  in  an  alternating  current  circuit. 

current  value  depends  directly  upon  the  capacitive  reactance  in 
a  circuit,  providing  the  average  value  of  E.  M.  F.  is  kept 
constant.  The  average  value  of  the  alternating  current  then 
increases  with  an  increase  in  either  the  average  E.  M.  F.  or 
the  capacitive  reactance  and  decreases  with  an  increase  of 
actual  resistance.  Capacitive  reactance  decreases  with  an  in- 
crease of  either  capacitance  or  frequency,  and  vice  versa. 

A  straight  wire  has  some  capacitance  which  increases  with 
the  length  of  the  wire.  Coiling  the  wire  will  also  increase  its 
capacitance.  But  since  inductance  is  the  predominant  prop- 
erty the  capacitance  of  a  wire  or  coil  is  very  small  in  com- 
parison. 

If  two  metallic  plates  are  assembled  with  a  sheet  of  glass 
between  them  there  is  produced  what  is  known  as  a 
' 'condenser."  This  arrangement  would  have  a  very  appreci- 
able capacitance.      To  increase   the  capacitance   of   this   con- 


24  A  B  C  OF  VACUUM  TUBES 

denser  we  could  (i)  increase  the  area  of  the  glass  and  the 
metallic  plates;  (2)  decrease  the  thickness  of  the  glass  (the 
distance  separating  the  metallic  plates)  ;  (3)  use  a  substance 
between  the  plates  which  has  a  higher  "dielectric  constant.' ' 
The  material  between  the  plates,  whatever  it  may  be,  is  called 
the  "dielectric"  and  although  it  may  not  be  an  absolute  insu- 
lator it  does  have  a  very  high  resistance,  usually,  to  the  passage 
of  a  current.  Air  is  assumed  to  have  a  "dielectric  constant" 
of  unity  (or  one)  and  if  a  condenser  with  the  same  dimensions 
has  a  dielectric  which  gives  five  times  the  capacity  of  the  air 
condenser,  the  "dielectric  constant"  of  the  other  material  is 
five.  Some  dielectric  constants  in  the  order  of  their  increase 
are:  Air — 1,  paraffine — 2;  hard  rubber — 2.5;  glass — 6  to  8; 
mica — 8. 

It  would  be  very  convenient  at  times  to  have  a  variable 
capacitance  whose  value  could  be  adjusted  at  will.    If  the  maxi- 

.'Terminafs--. 

*  si 


Stationary 
Plates-* 


<- Movable 
Plates 


Fig.  6 — Scheme  of  a  variable  condenser.     (If  the  movable  plates  are  made 
stationary   it    is    a    "fixed"    condenser.) 

mum  value  is  not  necessarily  very  large,  an  air  dielectric  may 
be  used.  A  number  of  movable  plates  could  be  arranged  so 
that  they  interleave  with  a  number  of  stationary  plates  without 
touching  them.  All  the  stationary  plates  are  connected  together 
and  to  a  terminal  and  the  movable  plates  are  connected  together 
and  to  a  second  terminal.     There  will  be  an  increase  in  the 


INTRODUCTORY 


25 


maximum  capacitance  obtainable  if  more  plates  are  used  be- 
cause this  will  increase  the  total  plate  area,  the  dielectric  being 
the  air  between  the  stationary  and  movable  plates.  Fig.  6 
shows  how  the  plates  are  interleaved  and  Fig.  7  illustrates 
a  variable  air  condenser  with  and  without  its  case. 

The  question  may  be  asked,  "How  does  an  electric  current 
flow  through  a  condenser  if  the  dielectric  is  a  good  insulator 


Connecting 
„     ,  Posts 

Scale 
in  Degrees^ 


Man  die  to  Rotate 
Movable  Plates 


Shaft  upon  which 
Movable  Plates  are 

Mounted 


'Insulating  Buttons 
..        ,,    n,  j     )  or  Washers  between 

Movable  Plates-  Plates 

Fig.  7 — Typical    variable   condenser    with    air    dielectric. 


and  prevents  the  passage  of  current?"  A  direct  current  will 
not  flow  through  a  condenser  and  neither  will  an  alternating 
current.  But  the  alternating  current  will  appear  to  flow 
through  because  in  all  parts  of  the  circuit  on  either  side  of  the 
dielectric  it  rises  and  falls  in  rate  of  flow  back  and  forth 
between  the  dielectric  and  the  source  of  E.  M.  F.  To  make  the 
matter  more  clear,  suppose  an  analogy  is  considered.  In 
Fig.  8  a  pipe  full  of  water  is  represented  with  an  elastic  parti- 
tion at  "A"  and  a  pump  at  "B."  The  pump  is  so  arranged 
that  the  to-and-fro  motion  of  the  piston  exerts  a  pressure 
periodically  in  one  direction  then  the  other  and   causes   the 


26 


A  B  C  OF  VACUUM  TUBES 


water,  therefore,  to  flow  in  each  direction  periodically.  The 
water  does  not  flow  past  the  elastic  partition  at  any  time.  But, 
the  elasticity  of  the  partition  allows  it  to  stretch  and  during 
the  time  the  current  is  forced  in  the  direction  of  the  full  line 
arrow,  it  stretches  and  exerts  a  back  pressure  upon  the  water 
exactly  equal  to  the  pressure  of  the  pump  at  every  instant. 
When  the  pump  pushes  the  water  in  the  opposite  direction  the 
partition  stretches  in  the  opposite  direction  and  again  exerts 
a  back  pressure  equal  at  every  instant  to  the  pump  pressure. 
There  is  thus  a  surge  of  water  back  and  forth  through  the 
pipe,  causing  the  partition  to  stretch  in  first  one  direction 
then  the  other,  within  the  limit  of  its  elasticity.  And,  then,  as 
far  as  the  pipe  is  concerned,  there  is  an  alternating  current 
of  water  in  it  in  spite  of  the  partition.  The  dielectric  of  a 
condenser  is  the  "partition"  and  it  must  have  electrical  elas- 


Elash'c 
Partition- 


Piston 
Rod-' 


B     Pump 


Fig.  8 — Water   analogy   of    alternating   current   in   a   circuit   containing   a 

condenser. 


ticity,  otherwise  it  might  be  ruptured  in  the  same  manner  that 
the  partition  in  the  pipe  would  be,  if  the  pump  pressure  became 
too  great.  It  is  thus  readily  seen  that  while  an  alternating 
current  does  not  actually  flow  through  the  dielectric,  the  cur- 
rent does  alternate  in  the  circuit  in  spite  of  the  dielectric. 


INTRODUCTORY  2J 


Resonance 


Suppose  two  tuning  forks  are  tuned  to  the  same  musical 
pitch  and  placed  a  foot  or  so  apart.  If  one  is  struck  a  light 
blow  it  vibrates  and  a  sound  is  heard  which  is  the  musical 
pitch  dependant  upon  the  rate  of  vibration  of  the  fork.  The 
fork  is  setting  up  waves  in  the  air  which  reach  the  ear  and 
are  translated  by  the  brain  into  a  musical  tone  which  is  recog- 
nized. What  is  perhaps  more  interesting,  however,  is  that 
the  second  tuning  fork  also  vibrates  in  sympathy  with  the 
first.  If  the  first  fork  is  grasped  in  the  hand  to  stop  its  vibra- 
tion, the  second  will  still  vibrate  for  a  short  time  and  emit  a 
musical  tone  exactly  of  the  same  pitch  as  the  first  one.  It 
is  evident  that  the  second  fork  is  vibrating  at  the  same  rate 
as  the  first  before  it  was  grasped.  It  is  said  to  be  "in  tune" 
or  "in  resonance"  with  the  first. 

Suppose,  however,  that  the  first  tuning  fork  is  adjusted  so 
that,  when  struck,  it  vibrates  at  a  different  rate.  This  time 
the  second  one  will  not  vibrate  in  sympathy  as  it  would  if  it 
also  had  been  adjusted  to  vibrate  at  the  same  rate.  The  two 
forks  are  then  not  in  tune  with  each  other  and  the  second  \% 
"out  of  resonance"  with  the  first. 

In  the  first  case  the  second  fork  was  forced  to  vibrate  at 
the  same  mechanical  frequency  (of  vibration)  as  the  first 
fork,  because  it  was  in  resonance.  In  the  second  case  there 
was  no  resonance,  so  the  second  fork  was  unaffected. 

An  electrical  circuit  in  which  an  alternating  current  flows 
does  not  vibrate  mechanically,  but  it  may  be  thought  of  as 
vibrating  electrically.  Also,  one  electrical  circuit  may  be  ad- 
justed so  that  it  is  "in  resonance"  with  another  and  so  that 
an  alternating  current  flowing  in  one  will  produce  an  alter- 
nating current  in  the  other  of  the  same  frequency.     In  this 


28 


A  B  C  OF  VACUUM  TUBES 


case  of  "electrical  resonance,"  the  second  circuit  is  caused  to 
'Vibrate  electrically"  in  sympathy  with  the  first. 

Oscillations 

Alternating  electrical  currents  of  extremely  high  frequency 
are  said  to  be  alternating  at  "radio  frequencies,"  as  has  been 
noted.      And   such  high    frequency   alternating   currents   are 


-f 


Zero 
Current' 


<- /Cycle 


*l 


-Amplitude 

Jn£o5{tlve_ I 

Direction  ' 

of  Flow 


•Amplitude  in 
Negative  Direction 
of  Flow 


Fig.  9 — Continuous    oscillations. 


called  "Radio  frequency  alternating  currents."  Instead  of 
using  this  long  name  a  shorter  one  has  been  selected  for  prac- 
tical use,  and  it  is  said  that  such  alternating  currents  are 
"oscillations."  A  definition  of  oscillations  may  then  be, 
"radio  frequency  alternating  current." 

The  maximum  value  of  current  strength  attained  in  each 
direction  of  current  flow  during  each  cycle  is  called  the  "ampli- 
tude." If  successive  amplitudes  are  of  equal  values  as  long  as 
the  current  flows,  the  oscillations  are  said  to  be  "continuous 
oscillations."  An  alternating  E.  M.  F.  of  constant  amplitude 
is,  of  course,  necessary  to  the  production  of  continuous  oscil- 


INTRODUCTORY 


29 


lations.  Fig.  9  may  assist  the  reader  to  understand  this  term. 
An  ordinary,  low  frequency,  alternating  current  also  has  con- 
stant amplitudes. 

If  an  E.  M.  F.  has  constantly  decreasing  amplitude  it  will 
produce  a  current  of  constantly  decreasing  amplitude.  Also, 
if  the  amplitudes  of  the  E.  M.  F.  decrease  rather  rapidly, 
the  current  will  cease  to  flow  after  a  short  period  of  time 
because  of  the  absence  of  E.  M.  F.  to  force  it  to  flow. 
If,  then,  the  successive  amplitudes  of  oscillations  decrease,  the 


•t 


^■5 


^t  Cycle ->\ 

t± 1  Train  of  Oscillations — ->j         k —  I  Train  of  Oscillations — >| 

.-Amplitudes  in 
Positive  Direction  \ 


Zero 
Current '' 


Is 


%  \  / 

''^Amplitudes  in 

Negative  Direction 
or  Flow 


Fig.  10 — Damped   oscillations. 


oscillations  may  be  said  to  be  "damped,"  and  there  is  produced 
what  are  called  "damped  oscillations."  Sometimes  continuous 
oscillations  are  referred  to  as  "undamped  oscillations,"  because 
their  successive  amplitudes  are  not  damped.  When  damped 
oscillations  finally  cease  they  are  said  to  be  "damped  out." 
Fig.  10  will  assist  in  understanding  this  matter.  Two  series,  or 
groups,  of  damped  oscillations  are  shown,  and  each  series  may 
be  referred  to  as  a  "train"  of  damped  oscillations. 

If  an  electrical  shock  were  given  to  a  circuit  containing 
inductance  and  capacitance,  that  is,   if  an  electrical  pressure 


3o  A  B  C  OF  VACUUM  TUBES 

were  suddenly  applied  and  immediately  withdrawn,  the  circuit 
would  vibrate  electrically  in  the  same  manner  as  the  struck 
tuning  fork  vibrated  mechanically.  An  alternating  current 
would  be  produced  in  the  circuit,  providing  its  resistance  were 
not  too  great,  but  the  successive  amplitudes  would  decrease 
and  the  oscillations  would  die  out  just  as  the  vibrations  of  the 
tuning  fork  die  out  a  short  while  after  the  fork  is  struck. 
In  the  second  circuit,  just  as  with  the  second  fork,  even  though 
there  is  resonance  the  vibrations  die  out  after  a  short  time. 

If,  however,  the  first  tuning  fork  were  tapped  very  lightly 
at  the  end  of  each  swing  it  would  continue  to  vibrate  as  long 
as  the  tapping  took  place  at  the  proper  times  and  in  the  proper 
amounts  to  maintain  these  vibrations  (or  swings).  The  regu- 
lar periodical  tapping  may  be  compared  to  a  regular  periodical 
E.  M.  F.  applied  in  an  electrical  circuit.  If  the  E.  M.  F.  is 
applied  at  the  proper  times  and  always  in  the  same  amounts, 
the  oscillations  will  not  decrease  in  amplitude  but  will  be  "con- 
tinuous." Now,  in  the  case  of  the  tuning  forks,  if  the  vibra- 
tions of  the  first  one  are  continuous  (due  to  continuously 
applied  taps),  the  vibrations  of  the  second  one  will  continue 
and  be  of  constant  amplitude.  Likewise,  in  a  second  electrical 
circuit,  if  the  oscillations  in  the  first  are  continuous  those  in 
the  second  will  also  be  continuous.  Continuous  oscillations  in 
a  second  circuit  are  then  the  result  of  a  continuously  applied 
E.  M.  F.  in  that  circuit  due,  in  turn,  to  a  continuously  applied 
E.  M.  F.  (and  therefore  oscillations  of  continuous  amplitude) 
in  the  first  circuit. 

The  action  of  producing  oscillations  in  a  second  circuit  by 
creating  oscillations  in  a  primary  circuit  is  called  "induction," 
and  we  may  say  that  when  oscillations  are  produced  in  a  sec- 
ondary circuit  they  are  "induced"  therein. 


INTRODUCTORY  31 

The  Reception  of  Signals 

It  should  now  be  quite  clear  that  if  oscillations  are  produced 
in  a  suitable  circuit  at  a  transmitting  station  oscillations  will 
be  produced  by  induction  in  a  suitable  circuit  at  a  receiving 
station,  when  the  two  circuits  are  in  resonance  with  each  other. 
Each  of  the  circuits  is  called  an  "antenna,"  or  sometimes,  an 
"aerial,"  since  each  is  frequently  erected  so  that  it  extends 
some  distance  from  the  earth  up  into  the  air. 

When  vibrations  are  induced  in  a  tuning  fork  by  another, 
the  air  between  them  is  set  in  motion  and  it  is  this  air  which 
transmits  the  motion  from  one  fork  to  the  other.  That  is, 
the  first  fork  sets  the  air  into  vibration  and  the  vibrating  air 
sets  the  second  fork  into  vibration.  Another  illustration 
would  be  the  dropping  of  a  stone  into  a  quiet  pond  of  water. 
Water  waves  radiate  from  the  point  where  the  stone  strikes 
the  water  until  they  reach  a  cork  located  a  distance  away.  The 
cork  is  set  into  motion  and  bobs  up  and  down,  or  oscillates. 
But  the  cork  does  not  move  further  away  from  or  closer  to 
the  point  where  the  oscillations  were  created  in  the  water.  This 
proves  that  the  water  itself  does  not  travel  from  one  place  to 
another  but  that  the  oscillating  motion  is  transmitted  or  radi- 
ated from  the  point  where  the  disturbance  occurs.  In  the 
case  of  either  the  air  or  the  water  it  is  the  oscillatory  or 
vibratory  motion  which  is  transmitted. 

This  throws  some  light  upon  electrical  induction,  But  in 
the  case  of  oscillations  produced  in  a  secondary  electrical 
circuit  neither  air  nor  Water  is  necessary  to  transmit  the  mo- 
tion. In  fact,  electrical  oscillations  in  a  circuit  have  no  effect 
upon  either  air  or  water.  There  must  be  some  medium,  how- 
ever, which  is  capable  of  being  set  into  vibration  by  the  elec- 
trical oscillations  and  will,  in  turn,  create  electrical  oscillations 


32  A  B  C  OF  VACUUM  TUBES 

in  a  distant  circuit.  This  medium  is  called  the  "ether,"  and  is 
one  which  pervades  all  space.  It  is  present  in  the  entire 
universe  where  water  and  air  may  be  entirely  absent.  It  is, 
in  fact,  the  ether  which  is  set  into  vibration  by  the  oscillations 
in  a  transmitting  antenna.  These  vibrations  spread  out  in 
circles  just  like  the  ripples  in  the  water  after  a  stone  is 
dropped  and  when  they  reach  a  receiving  antenna,  create  elec- 
trical oscillations  in  that  circuit.  The  whole  purpose  of  "radio" 
is  to  create  ether  vibrations  and  to  translate  them  at  a  distant 
point. 

Now,  assume  that  continuous  oscillations  or  recurrent  trains 
of  damped  oscillations  are  produced  in  a  transmitting  antenna 
and  either  continuous  or  recurrent  trains  of  damped  oscilla- 
tions are  induced  in  the  receiving  antenna.  We  still  lack,  a 
device  to  make  the  received  oscillations  perceptible  to  one  of 
our  senses.  But  in  a  following  chapter  means  for  accom- 
plishing this  necessary  result  are  considered. 

Wave  Length 

The  ether  vibrations  or  oscillations  have  the  same  frequency 
as  the  electrical  oscillations  which  create  them.  Moreover, 
this  oscillatory  motion  of  the  ether  is  projected  through  it 
with  the  speed  of  light,  light  being  only  ether  vibration  at 
considerably  different  frequencies.  This  rate  of  speed  is 
300,000,000  meters  (approximately  186,000  miles)  per  sec- 
ond of  time.  Almost  too  rapid  a  rate  to  conceive — in  fact, 
ether  oscillations  caused  by  electrical  oscillations  travel  over 
seven  times  around  the  earth  in  one  second. 

The  ripples  created  in  a  pond  of  water  by  the  dropping  of  a 
stone  travel  about  10  to  100  centimeters  per  second,  a  centi- 
meter being  roughly  equivalent  to  one-hundredth  of  a  yard. 


INTRODUCTORY  33 

The  ripples  are,  of  course,  small  water  waves,  and  if  we  know 
their  rate  of  travel  and  their  frequency  of  production,  we  can 
easily  calculate  the  length  of  one  wave.  For  example,  one 
wave  is  produced  each  second  and  travels  a  distance  of  one 
yard  in  that  length  of  time.  What  is  the  length  of  the  wave? 
It  is,  of  course,  the  rate  of  travel  (one  yard  in  one  second) 
divided  by  the  frequency  of  wave  production  (one  cycle  per 
second  or  one  wave  per  second),  and  equals,  in  this  case,  one 
yard.  Likewise,  if  an  ether  wave  travels  300,000,000  meters 
per  second  and  the  frequency  of  its  oscillation  is  300,000,  its 
length  must  be  1,000  meters.  That  is,  the  wave  length  (length 
of  one  wave)  is  the  result  of  dividing  the  velocity  (distance 
traveled  per  second)  by  the  frequency  (number  of  waves  per 
second).  There  are,  of  course,  the  same  number  of  waves  per 
second  as  cycles  of  oscillation.  In  speaking  of  these  ether 
vibrations  it  is  customary  to  think  of  their  wave  length  rather 
than  their  frequency.  If  a  transmitting  station  is  said  to 
"radiate"  a  "wave  length"  of  200  meters,  what  is  meant  is 
that  the  ether  in  the  neighborhood  of  the  transmitting  antenna 
is  set  into  vibration  at  the  rate  of  1,500,000  times  per  second 
(frequency  equals  1,500,000)  and  that  the  length  of  each 
ether  wave  created  is  200  meters 

Tuning  the  Receiving  Antenna 

Under  "Inductance"  and  "Capacitance"  it  was  brought  out 
that  inductive  reactance  has  the  effect  of  a  resistance  upon  an 
alternating  current  and  that  capacititive  reactance  has  just  the 
the  opposite  effect.  It  was  also  brought  out  that  inductive 
reactance  increases  and  capacitive  reactance  diminishes  with 
increased  frequency  and  vice  versa.  If,  then,  a  circuit  has  an 
inductance  and  a  capacitance  selected  at  random  there  will  be  a 
certain  frequency  at  which  the  two  reactances  are  equal  and, 


34  A  B  C  OF  VACUUM  TUBES 

since  they  are  exactly  opposite,  the  total  reactance  is  zero.  This 
frequency  is  called  the  "resonance  frequency."  On  the  other 
hand,  if  a  certain  frequency  is  selected  at  random  then  the  two 
reactances  must  be  adjusted  so  that  they  are  equal  for  this  fre- 
quency and,  since  they  are  opposite,  they  will  then  neutralize 
each  other  and  the  total  reactance  will  be  zero. 

Now,  when  a  receiving  antenna  is  acted  upon  by  ether  vibra- 
tions of  a  certain  definite  frequency  (the  frequency  of  the  oscil- 
lations in  the  transmitting  antenna)  an  alternating  (oscillating) 
E.M.F.  is  produced  and  an  oscillating  current  will  tend  to  flow 
in  the  antenna.  Whether  or  not  the  current  will  actually  flow 
and  whether  it  will  be  of  maximum  value  for  the  E.M.F. 
applied,  will  depend  upon  both  the  actual  resistance  and  the 
total  reactance  (effective  resistance)  in  the  antenna  circuit. 
The  actual  resistance  may  be  assumed  to  be  and  in  practice  is, 
fairly  low,  and  with  an  antenna  already  erected  it  is,  on  the 
whole,  a  fixed  value.  The  current  then  depends  upon  the  total 
reactance  which,  as  has  been  stated,  may  be  made  zero  by  the 
proper  adjustment  of  inductive  and  capacitive  reactance.  If  the 
reactances  are  made  equal  for  this  definite  applied  frequency 
then  the  antenna  may  be  said  to  be  "tuned"  or  "in  resonance" 
with  the  frequency  and  therefore  with  the  frequency  of  oscilla- 
tions in  the  transmitting  antenna.  Since  inductive  reactance 
may  be  increased  and  decreased  by  varying  the  number  of  turns 
of  wire  on  a  coil  and  since  capacitive  reactance  may  be  increased 
and  decreased  by  allowing  the  movable  plates  of  a  variable  air 
condenser  to  interleave  to  a  greater  or  lesser  extent,  tuning 
may  be  accomplished  by  either  a  variable  coil  or  a  variable 
condenser. 

Increasing  the  inductance  of  the  coil  or  the  capacitance  of  the 
condenser  means  that  the  resonant  frequency  is  decreased,  pro- 
viding the  coil  and  condenser  are  in  series  with  each  other  in  the 


INTRODUCTORY  35 

circuit.  That  is,  if  the  circuit  is  in  resonance  with  a  certain  fre- 
quency and  either  the  inductance  of  the  coil  or  the  capacitance  of 
the  condenser  is  increased,  the  circuit  is  no  longer  in  resonance 
with  this  frequency  but  would  be  in  resonance  with  a  lower 
frequency  of  ether  oscillations  produced  by,  perhaps,  some  other 
transmitting  antenna.  The  counter  condition  is  of  course  true, 
that  if  the  coil  inductance  or  the  condenser  capacitance  were  de- 
creased, the  circuit  would  then  be  in  resonance  with  a  higher 
frequency  of  ether  oscillations  produced,  possibly,  by  still  an- 
other transmitting  station.  Either  one  of  these  stations  or  any 
one  of  possibly  a  large  number  of  stations  might  then,  of 
course,  be  picked  up  at  will  by  simply  tuning  the  receiving  an- 
tenna circuit  in  this  manner. 

Wave-length  of  ether  oscillations  is  perhaps  thought  of  more 
popularly  than  frequency,  and  under  "Wave  Length"  it  was 
pointed  out  that  as  the  frequency  of  oscillations  increases  their 
wave  length  diminishes  and  vice  versa.  If,  then,  we  wish  to 
speak  in  terms  of  wave-length,  we  may  say  that  an  increase  of 
inductance  or  capacitance  in  a  receiving  circuit  increases  the 
wave  length  at  which  that  circuit  is  in  resonance  and  that  a  de- 
crease of  either  of  them  decreases  this  wave  length.  Speaking 
still  in  terms  of  wave  length  rather  than  frequency,  it  may  now 
be  said  that  tuning  is  simply  the  process  of  adjusting  inductive 
reactances  (coils)  and  capacitive  reactances  (condensers)  in  a 
circuit  so  that,  for  the  wave  length  of  the  ether  oscillations  act- 
ing upon  the  (antenna)  circuit,  the  two  reactances  are  equal 
and,  being  opposite,  neutralize  each  other  to  reduce  the  total 
reactance  to  zero. 

The  Antenna  as  a  Complete  Circuit 

As  a  general  rule,  the  antenna  appears  not  to  be  a  complete 
circuit.    If  Fig.  1 1  is  considered  it  is  seen  that  there  is  a  capaci- 


36 


A  B  C  OF  VACUUM  TUBES 


tance  effect  (or  a  condenser  effect)  between  the  free  end  of  the 
antenna  and  the  end  connected  to  earth  or  to  a  "counterpoise" 
consisting  of  a  number  of  wires  stretched  beneath  the  antenna. 
That  is,  every  inch  of  the  antenna  has  a  capacitance  to  earth 
(or  to  the  counterpoise)  so  that  considering  the  antenna  as  a 


Antenna      ■% 
Supported  • 
herey 


Note <    There  is  Distributed  Inductance  over  the 
Length  of  Antenna  and  Down-Lead 


<-■ Antenna  Down -Lead 

{  ^Antenna  Terminal 


Variable  Coil 
(  Variable  Lumped 
Inductance) 


jx-----  Antenna 
Supported 
here 


Effective  . 
Capacitance  ' 
'Distributed) 


# 


Ground 
Terminal--'*! 


Variable  Condenser 

(Variable  Lumped 

Capacitance) 


~  Earth 

or  Counterpoise 

Fig.  II — Scheme  of   antenna  as  a  complete   circuit. 

whole,  it  may  be  regarded  as  one  plate  of  a  condenser,  with  the 
earth  or  counterpoise  acting  as  the  other  plate.  There  is  then 
a  circuit  which  is  closed  so  far  as  alternating  current  (especially 
radio- frequency  alternating  current)  is  concerned  and  cur- 
rent readily  flows  in  the  circuit  under  the  proper  conditions 
mentioned  above. 

The  reason  that  an  antenna,  particularly  a  transmitting  an- 
tenna, has  to  be  elevated  a  considerable  distance  above  the  earth 
is  in  order  to  allow  a  large  amount  of  ether  to  be  acted  upon 
and  set  in  motion  by  the  antenna  oscillations.  It  is  readily  seen 
that  the  higher  the  antenna  the  larger  the  amount  of  ether  there 
is  between  its  top  and  the  surface  of  the  earth.  In  the  case  of 
a  receiving  antenna  this  also  applies  to  a  considerable  extent, 
since  in  this  case  it  is  desirable  to  have  as  large  an  amount  of 


INTRODUCTORY  37 

vibrating  ether  acting  upon  the  circuit  as  possible.  The  re- 
sponse in  a  device  to  make  signals  perceptible  to  our  senses 
depends  very  greatly  upon  the  auxiliary  devices  used,  and  it  is 
possible  to  provide  such  sensitive  apparatus  and  to  amplify  cur- 
rents so  greatly  that  a  low  receiving  antenna  may  be  entirely 
permissible.  The  devices  to  be  considered  in  the  following 
chapters  are  indeed  so  sensitive  and  can  be  made  to  amplify 
currents  to  such  great  extents  that  receiving  antennae  may  even 
be  done  away  with  in  practise.  It  must  be  borne  in  mind, 
however,  that  no  matter  how  efficient  the  receiving  apparatus 
may  be,  better  results  are  obtained  with  the  use  of  antennae 
which  are  the  better,  the  higher  they  are  erected. 

In  the  following  chapters  the  little  lamps  called  "vacuum 
tubes"  "audions,"  "radiotrons,"  and  so  forth,  are  considered. 
Results  obtained  with  them  are  truly  remarkable  and  it  is  due 
to  their  adoption  that  such  long  ranges  are  now  possible  in 
radio  communication  without  any  increase  in  the  power  of 
transmitting  stations.  Their  action  is  truly  absorbingly  inter- 
esting. 


CHAPTER  II. 

THE  VACUUM  TUBE  AS  A  RECTIFIER  AND  RELAY  WITHOUT 

MOVING  PARTS 

Tube  construction — The  Edison  Effect — Electron  emission  from  a 
heated  filament — Dependence  of  plate  current  upon  plate  potential — 
Dependence  of  plate  current  upon  filament  current — Effect  of  grid  poten- 
tial upon  plate  current — Relay   action — Rectification. 

Tube  Construction 

A  vacuum  tube  is  somewhat  similar  in  construction  to  an 
ordinary  incandescent  electric  lamp  which  has  a  filament  sup- 
ported inside  a  glass  tube  or  bulb  from  which  the  air  has  been 
exhausted.  When  an  electric  current  flows  through  the  lamp 
filament  it  is  heated  to  incandescence  and  produces  light.  A 
vacuum  tube  also  has  a  filament  which  may  be  made  incan- 
descent by  allowing  electric  current  to  flow  through  it,  but  the 
production  of  light  in  this  case  is  merely  an  accompaniment  of 
more  essential  phenomena  as  will  be  explained. 

When  air  is  exhausted  from  any  kind  of  a  vessel  a  vacuum 
remains  and  the  degree  of  vacuum  depends  upon  the  degree 
of  air  exhaustion.  The  vacuum  within  a  so-called  "vacuum 
tube"  is  very  much  higher  than  that  within  an  incandescent 
electric  lamp.  What  are  known  as  "hard"  tubes  have  an 
extremely  high  vacuum,  -often  indeed  the  highest  possible 
vacuum  attainable.  Others  known  as  "soft"  tubes  contain  a 
small  amount  of  gas  and,  therefore,  a  somewhat  lower  vacuum. 
Each  class  of  tube  has  its  particular  uses,  although  the  "hard" 
tubes  may  be  used  for  all  purposes. 

Regardless  of  the  degree  of  vacuum,  a  tube  contains,   in 

38 


VACUUM  TUBE  AS  RECTIFIER  AND  RELAY 


39 


addition  to  a  filament,  a  "grid"  and  a  "plate"  arranged,  for 
example,  as  in  Fig.  12.  The  grid  is  always  placed  between 
the  filament  and  the  plate. 

The  filament  is  usually  of  very  fine  tungsten  wire  and  may 
be  straight,  "V"  shaped  or  shaped  like  a  "W."     The  apexes 


Spiral 
Grid 


Filament  — - 

Plate 
Support  - 

Filament 
Support 

Glass  Stem-- 


Cement  Holds 
Tube  in  Base  ~- 


Glass  Wall  of  Tube 

■-Filament 

Support 
\  (Springy) 

Plate  (cut  away) 

Grid  Support 

-Wires Sealed  here 
<■  Leading-in 
Wires 

-Brass  Shell  Base 


<— -Prongs 
Fig.  12 — Construction    of    a    typical    vacuum    tube. 


of  the  "V"  and  "W"  shaped  filaments  are  upwards.  No  matter 
what  the  filament  shape,  it  is  supported  in  such  a  manner  as 
to  prevent  its  displacement  when  jarred.  The  tube  of  Fig.  12 
has  a  straight  tungsten  filament  supported  at  its  upper  end 
by  a  nickle  rod,  to  which  it  is  carefully  welded.  The  lower 
end  of  the  filament  wire  is  welded  to  a  shorter  nickle  rod 
and  both  rods  are  anchored  into  a  glass  stem.  The  longer 
rod  is  springy,  so  that  it  will  hold  the  filament  taught. 


40 


VACUUM  TUBE  RECTIFIER 


The  grid  may  be  a  mesh  of  nickle  wire  wound  about  two 
supports.  In  the  figure  it  is  shown  as  a  spiral  or  helix,  so 
supported  by  a  nickle  rod  that  the  filament  becomes  the  axis 
of  the  spiral.  Each  turn  of  the  spiral  grid  is  welded  to  a 
nickle  supporting  rod,  the  lower  end  of  which  is  anchored  into 


Fig.  13 — Various    forms   of    vacuum   tubes   and    sockets. 


the  glass  stem.     The  grid  must,  in  any  case,  be  rigid  enough 
to  withstand  considerable  jarring. 

The  plate  may  be  of  molybdenum,  nickle  or  thin  sheet  steel. 
It  is  quite  often  cylindrical  in  shape,  but  may  also  be  flat  or 
shaped  like  a  cylinder  flattened  out  on  two  sides.     The  plate 


VACUUM  TUBE  AS  RECTIFIER  AND  RELAY       41 


---> 


'urrenf 


Neg.  Filament 
Terminal 


Plate 


Pos.  Potential 
on  Plate 


Pos .  Battery 
+  0    Terminal 


Fila- 
ment 


Rheo- 


Bat- 
tery 


Plate        = 
Battery    —    <• 

Neg.  BatteryK 
Terminal  >» 


^oo/y 


Current  Indicating  Device 

(A) 
Plate    Current  Flows. 


Gr/a' 


/\ 


ment 


Plate 


Neg.  Potential 
on  Plate 


Neg.  Filament 
Terminal 


Neg.  Battery 
■  0_  Terminal 


Plate 


Battery 


Pos.  Battery^  -t-" 
Terminal 


**Ooff 


Current  Indicating  Device 

(B) 
No  Plate  Current  Flows. 


Fig.  14 — The   Edison   Effect   or   one   way   conduction   of    electric   current 

within  a  vacuum  tube. 


42  A  B  C  OF  VACUUM  TUBES 

must  also  be  rigidly  supported.  In  the  figure  there  is  a  cylin- 
drical plate  of  nickle  so  supported  by  a  nickle  rod  that  it 
encloses  the  grid  and,  therefore,  the  filament.  The  filament 
is  then  the  axis  of  both  the  spiral  grid  and  the  cylindrical 
plate.  The  plate  support  is  welded  to  the  plate  and  the  lower 
end  of  the  support  is  securely  anchored  into  the  glass  stem. 

There  are,  then,  three  members  called  "electrodes,"  the 
filament,  the  grid  and  the  plate.  A  vacuum  tube  is  seen  to  be 
a  somewhat  more  complicated  device  than  the  incandescent 
electric  lamp. 

The  four  prongs  which  extend  below  the  base  of  the  tube 
are  for  connection  into  a  circuit.  Each  of  these  is  welded  to 
a  leading-in  wire  which  connects  it  to  a  support.  In  this 
manner  the  two  filament  ends,  the  grid  and  the  plate  are  each 
connected  to  a  prong.  The  leading-in  wires  are  very  carefully 
welded  to  the  supports  and  sealed  into  the  glass  stem,  so  that 
at  no  future  time  may  there  be  any  leakage  of  air  into  the 
tube.     Air  leakage  would  render  the  tube  unfit  for  use. 

Fig.  13  illustrates  a  few  of  the  various  forms  of  tubes 
and  some  tube  sockets  or  receptacles.  When  a  tube  is  inserted 
into  a  socket,  each  tube  prong  makes  contact  with  a  spring 
contact  piece  which  is  connected  to  a  terminal  binding  post. 
Two  binding  posts  are  for  the  filament  connections  and  one 
each  is  for  the  grid  and  the  plate.  This  provides  a  convenient 
way  of  holding  a  tube  and  connecting  it  into  a  circuit. 

The  Edison  Effect 

In  both  Fig.  14- A  and  14-B  there  is  a  battery  called  the 
"plate"  or  "B"  battery  connected  between  the  plate  and  one 
of  the  filament  leads.  In  each  figure,  also,  a  very  sensitive 
current  indicating  device  is  connected  into  the  plate  circuit. 
Current  may  be  allowed  to  flow  through  the  filament  from  a 


VACUUM  TUBE  AS  RECTIFIER  AND  RELAY       43 

smaller  battery  called  the  "filament"  or  "A"  battery.  The 
current  flowing  through  the  filament  may  be  controlled  by  a 
variable  resistance  in  the  filament  circuit.  This  variable 
resistance  is  called  a  "rheostat.' '  Increasing  this  resistance 
causes  decreased  filament  current  arid  vice  versa.  Also,  of 
course,  if  the  filament  rheostat  is  turned  off,  no  current 
flows  in  the  filament.  When  there  is  no  current  flowing 
in  the  filament  it  is  cold,  but  when  current  is  allowed  to 
flow,  the  filament  is  thereby  heated  to  a  temperature  depending 
upon  the  current  strength.  The  filament  rheostat  may,  there- 
fore, be  used  to  control  the  filament  temperature  by  controlling 
the  filament  current. 

Suppose  that  the  filament  current  is  turned  off  (filament 
cold)  and  the  positive  terminal  of  the  plate  battery  is  con- 
nected to  the  plate,  as  in  Fig.  14-A.  Observation  of  the 
current  indicating  device  shows  that  no  current  flows  in  the 
plate  circuit. 

With  the  filament  still  cold  (rheostat  turned  off)  the  plate 
battery  connections  are  reversed  so  that  the  negative  terminal 
of  the  battery  is  connected  to  the  plate,  Fig.  14-B.  Observa- 
tion again  shows  that  there  is  no  current  flowing  through  the 
indicating  device. 

The  negative  terminal  of  the  plate  battery  is  still  connected 
to  the  plate  and  the  rheostat  is  now  turned  on,  allowing  enough 
current  to  flow  through  the  filament  to  heat  it  to  incandescence. 
Observation  once  again  shows  no  current  in  the  plate  circuit 
through  the  indicating  device. 

Now,  with  the  filament  still  glowing,  the  plate  battery 
connections  are  changed  back  again  so  that  the  positive  battery 
terminal  is  connected  to  the  plate,  as  in  Fig.  14-A.  This 
time  there  is  an  appreciable  current  indicated  as  flowing  in 
the  plate  circuit  from  the  positive  terminal  of  the  battery  to 


44  A  B  C  OF  VACUUM  TUBES 

the  plate,  across  the  space  within  the  tube  to  the  filament  and 
back  to  the  battery.  This  is  an  interesting  state  of  affairs. 
A  direct  current  of  electricity  is  flowing  from  the  plate  to 
the  filament  through  the  vacuum  of  the  tube.  There  is  elec- 
trical conduction  between  these  two  points,  but  only  when 
the  filament  i  glowing  and  the  plate  is  connected  to  the 
positive  terminal  of  the  plate  battery. 

This  phenomenon  of  one  way  conduction  of  electric  current 
through  a  vacuum  was  noted  by  Thomas  A.  Edison  and  is 
termed  "the  Edison  effect."  Like  numerous  other  discoveries, 
however,  it  was  not  fully  investigated  and  used  until  some 
time  later. 

Electric  current  always  flows  or  tends  to  flow  from  a  point 
of  high  to  a  point  of  low  potential,  This  may  be  compared 
to  the  flow  of  water  down  a  hill.  A  point  in  the  stream  at 
the  top  of  the  hill  is  at  a  higher  "potential"  than  a  point  in 
the  same  stream  at  the  bottom  of  the  bill.  In  the  case  of  elec- 
tricity, the  high  potential  point  is  said  to  be  the  point  of 
"positive"  potential  and  the  lower  potential  point  that  of 
"negative"  potential.  An  electric  current,  therefore,  flows  or 
tends  to  flow  always  from  a  point  of  positive  to  a  point  of 
negative  potential.  When  the  positive  terminal  of  the  plate 
battery  is  connected  to  the  plate,  the  potential  of  the  plate  is 
positive  with  respect  to  that  of  the  filament,  because  current 
will  flow  from  the  plate  to  the  filament,  inside  the  tube, 
providing  the  filament  is  lighted.  The  glowing  filament,  in 
this  case,  causes  the  path  or  circuit  from  plate  to  filament  to 
be  closed. 

Electron  Emission  from  a  Heated  Filament 

The  smallest  possible  particle  of  negative  electricity  is  called 
an  "electron."     The  word  means  "carrier  of  electricity."     An 


VACUUM  TUBE  AS  RECTIFIER  AND  RELAY       45 

electron  is  then  the  smallest  possible  negative  electric  charge 
and  is,  moreover,  a  carrier  of  electricity.  When  the  filament 
is  heated,  by  the  electric  current  flowing  through  it,  thousands 
of  these  electrons  are  projected  at  high  velocity  from  it  like 
buckshot  from  a  shotgun.  The  higher  the  filament  tempera- 
ture the  more  electrons  there  will  be  projected  in  any  given 
length  of  time.  Now,  when  the  filament  projects  an  electron 
from  itself,  it  loses  a  minute  portion  of  its  negative  charge 
and,  since  the  negative  and  positive  charges  are  normally 
equal,  if  the  filament  loses  some  of  its  negative  charge,  the 
charge  remaining  upon  it  is  positive.  If  there  is  nothing  to 
prevent  it,  then,  the  filament  will  attract  electrons  back  to 
itself  at  the  same  rate  as  they  are  emitted.  Considering  the 
space  within  the  tube,  there  are  electrons  in  constant  motion, 
some  away  from  and  some  back  to  the  filament.  It  must  be 
remembered  that  unlike  charges  of  electricity  attract  each  other 
and  that  like  charges  repel  each  other. 

If  the  plate,  however,  is  now  given  a  positive  charge  by 
connecting  it  to  the  positive  terminal  of  a  battery,  as  in 
Fig.  14-A,  it  will  attract  to  itself  at  least  a  portion  of  the 
electrons  present  in  the  tube  space.  These  electrons,  being 
current  carriers,  then  cause  a  current  of  electricity  to  flow 
from  the  plate  to  the  filament  and  back  through  the  battery, 
the  battery  being  the  source  of  the  current.  That  is,  when 
electrons  are  attracted  to  the  plate  the  space  between  it  and 
the  filament  is  made  conducting  and  a  current  flows  from  the 
battery.  The  strength  (or  rate  of  flow)  of  this  plate  current 
depends  upon  the  number  of  electrons  (current  carriers)  which 
bridge  the  filament-plate  space  per  unit  of  time.  In  other 
words,  the  current  depends  upon  the  rate  at  which  electrons 
are  attracted  to  the  plate. 

If  the  plate  is  negatively  charged    (its  potential  negative 


46  A  B  C  OF  VACUUM  TUBES 

with  respect  to  the  filament)  no  plate  current  can  flow  because 
the  plate  repels  the  electrons.  (Like  charges  repel).  That  is, 
if  there  are  no  electrons  bridging  the  space  between  filament 
and  plate  no  conduction  can  take  place. 

This,  then,  explains  why  there  is  electrical  conduction 
through  a  vacuum  when  the  filament  is  glowing  and  the 
plate  is  positively  charged  and,  also,  why  there  is  no  conduc- 
tion when  the  plate  is  negatively  charged  or  the  filament  is 
cold. 

Dependence  of  Plate  Current  upon  Plate  Potential 

The  positive  potential  of  the  plate  determines  the  number 
of  electrons  which  may  be  attracted  to  it  per  unit  of  time 
and,  therefore,  the  strength  of  the  plate  current.  But  suppose 
that  the  plate  potential  has  been  increased  up  to  the  point 
where  electrons  are  attracted  just  as  rapidly  as  they  are  shot 
from  the  filament  into  the  tube  space.  A  higher  plate  potential 
will  not  be  able  to  attract  them  in  any  greater  numbers,  per 
unit  of  time,  because  it  is  already  attracting  them  just  as  fast 
as  they  are  being  emitted  from  the  filament.  There  is  a  limit, 
then,  to  the  increase  of  plate  current  with  an  increase  of  plate 
potential.  If  larger  plate  current  is  desired,  electrons  must 
be  projected  from  the  filament  in  greater  numbers. 

The  value  of  the  positive  potential  on  the  plate  depends 
upon  the  voltage  of  the  plate  battery.  Therefore,  in  view 
of  the  foregoing,  the  plate  current  increases  with  the  battery 
voltage  only  up  to  a  certain  point,  providing  no  change  is 
made  in  the  filament  current.  If  the  filament  current  is 
increased  by  a  certain  amount,  the  plate  current  increases, 
with  increase  in  battery  voltage,  up  to  a  new  point,  after 
which  no    further   current   increase   may   be   had   unless   the 


VACUUM  TUBE  AS  RECTIFIER  AND  RELAY       47 

filament  current  is  again  increased.  There  is,  of  course,  a  limit 
to  the  current  which  may  be  made  to  flow  through  the  fila- 
ment if  it  is  not  to  be  burned  out.  There  is  then  a  final  limit 
to  the  current  which  can  flow  in  the  plate  circuit  no  matter 
how  high  the  plate  battery  voltage  may  be  made.  In  practice, 
it  is  desirable  to  burn  the  filament  at  a  moderate  temperature 
and  to  secure  the  desired  plate  current  by  selecting  the  proper 
plate  battery  voltage.  This  will  lengthen  the  life  of  the  tube 
filament. 

Dependence  of  Plate  Current  upon  Filament  Current 

The  rate  of  electron  emission  increases,  as  has  been  said, 
with  the  increase  of  filament  current  (increase  of  filament 
temperature).  If  the  plate  potential  is  held  at  a  constant 
value  and  the  filament  current  is  increased,  there  will  be  an 
increase  of  plate  current  up  to  a  certain  point.  The  point 
where  no  further  increase  of  plate  current  is  had  with  increasing 
filament  current  is  that  at  which  the  filament  is  emitting  elec- 
trons as  fast  as  the  plate  can  attract  them.  Then,  no  matter 
how  much  faster  the  electrons  are  shot  from  the  filament 
into  the  tube  space,  the  plate  will  only  attract  a  certain  number 
of  them  per  unit  of  time. 

If  the  electrons  are  emitted  at  still  increasing  rates  there 
will  be  no  increase  of  plate  current  unless  the  potential  of  the 
plate  is  raised  (plate  battery  voltage  increased)  in  order  that 
the  plate  may  attract  them  in  greater  numbers  per  unit  of  time. 

If  there  are  more  electrons  emitted  by  the  filament  per  unit 
of  time  than  the  plate  can  attract,  some  of  the  electrons  in 
the  tube  space  are  continually  reaching  the  plate  while  others 
are  falling  back  upon  the  filament. 

Another   way   of   viewing  this   matter   is   to   consider   the 


48  A  B  C  OF  VACUUM  TUBES 

lumped  effect  of  all  the  electrons  in  the  tube  space  between 
filament  and  plate.  Since  each  electron  is  a  negative  charge, 
the  total  electric  charge  in  the  space  is  negative.  There  are, 
then,  two  electric  charges  acting  upon  the  electrons  just  leaving 
the  filament.  One  is  the  positive  charge  of  the  plate  and 
the  other  is  the  negative  charge  of  the  space  (negative  space 
charge).  If  the  positive  charge  of  the  plate  is  greater  than 
the  negative  charge  of  the  space,  electrons  will  be  drawn  to 
the  plate  from  the  space  and  others  will  be  pulled  into  the 
space  (from  the  filament)  to  take  their  places.  But  if  the 
positive  plate  charge  is  exactly  neutralized  by  the  negative 
space  charge,  this  space  charge  will  repel  one  electron  back 
to  the  filament  for  every  extra  electron  projected  from  the 
filament  into  the  space.  Only  a  certain  number  of  electrons 
per  unit  of  time  are,  therefore,  attracted  to  the  plate  and  the 
plate  current  is  at  maximum  value.  This  is  called  the  "space 
charge  effect." 

Suppose  that  some  concrete  hypothetical  examples  are  con- 
sidered. The  plate  potential  is  assumed  to  be  at  such  a  posi- 
tive value  (due  to  plate  battery  voltage)  that  it  can  attract 
iooo  electrons  per  second.  The  filament  temperature  is  low, 
at  the  start,  and  only  ioo  electrons  are  emitted  from  it  per 
second.  The  ioo  electrons  are  shot  into  the  tube  space  each 
second  to  make  the  negative  space  charge  at  all  times  equal 
to  that  of  ioo  electrons.  The  plate  charge  is  greater,  however, 
and  pulls  electrons  out  of  the  tube  space  at  the  rate  of  ioo 
per  second.  This  corresponds  to  a  certain  value  of  plate 
current.  Now,  the  filament  temperature  is  increased  and  500 
electrons  are  emitted  per  second.  The  plate  will  attract  500 
electrons  per  second  and  the  plate  current  is  increased.  The 
effect  of  the  plate  charge  is  still  greater  than  that  of  the  space 
charge.      The   filament   temperature   is   again   increased   and 


VACUUM  TUBE  AS  RECTIFIER  AND  RELAY       49 

to  such  an  extent,  this  time,  that  1000  electrons  are  emitted 
per  second.  The  plate  now  attracts  1000  electrons  per  second 
from  the  space.  The  effect  of  the  plate  charge  is  now  equal 
to  that  of  the  space  charge,  so  that  for  every  electron  shot 
into  the  space,  one  is  attracted  to  the  plate.  But  now 
suppose  that  the  filament  temperature  is  again  increased 
until  1500  electrons  are  emitted  per  second.  There  are  now 
1500  electrons  present  in  the  space  each  second.  The 
plate  can  only  attract  1000  of  them  from  the  space  so 
the  negative  space  charge  repels  the  extra  500  back  to  the 
filament.  The  plate  current  does  not  increase,  because  no 
matter  how  many  electrons  over  1000  per  second  are  emitted, 
only  that  number  per  second  are  actually  drawn  to  the  plate 
from  the  space.  If  the  potential  of  the  plate  is  raised  until 
it  is  able  to  attract  1500  electrons  per  second,  the  plate  current 
increases  until  the  plate  is  actually  attracting  1500  electrons 
to  it  each  second.  Then  the  space  charge  again  equals  the 
plate  charge  and  if  electrons  are  emitted  at  a  still  greater  rate, 
say  2000  per  second,  there  are  still  only  1 500  reaching  the  plate 
per  second  and  the  plate  current  remains  constant  at  the  higher 
value. 

Effect  of  Grid  Potential  upon  Plate  Current 

It  has  been  pointed  out  that  the  grid  electrode  is  located  be- 
tween the  filament  and  the  plate  of  a  tube.  The  grid  must  then, 
of  course,  be  situated  in  the  region  of  the  space  charge. 

If  a  positive  potential  is  applied  to  the  grid  by  a  grid  battery, 
as  in  Fig.  15,  its  potential  is  positive  with  respect  to  the  filament 
and  the  positive  charge  thus  placed  upon  the  grid  neutralizes 
some  of  the  effect  of  the  space  charge.  The  result  is  an  increase 
in  plate  current  and  the  grid  may  be  said  to  be  adding  the  effect 
of  its  positive  charge  to  that  of  the  plate  in  order  to  cause  more 
electrons  per  second  to  be  attracted  to  the  latter.   If  the  positive 


5o 


A  B  C  OF  VACUUM  TUBES 


charge  on  the  grid  is  sufficiently  increased,  however,  the  plate 
current  ceases  to  increase  because  electrons  are  then  being  at- 
tracted to  the  plate  just  as  rapidly  as  possible.  A  saturation 
point  is  then  reached.  When  the  grid  is  positively  charged  it 
will  also  attract  some  electrons  to  itself  and  cause  a  current  to 


6rid        Meg. 
Battery 


Grid 


A 


Fil. 


Plate 


+  <\Pos 


Plate 


~=~  Battery 
-§Neg. 


Current  Indicating 
Device 


Fig.  15 — One  method  of  varying  the   grid  potential. 


flow  in  the  grid  circuit,  from  grid  to  filament  inside  the  tube. 
This  grid  current  also  increases,  up  to  a  certain  point,  with  the 
increase  in  positive  grid  potential. 

If  a  negative  potential  is  applied  to  the  grid  from  the  grid 
battery,  its  effect  will  be  added  to  that  of  the  space  charge.  The 
result  is  a  decrease  of  plate  current  and  the  grid  may  be  said  to 
be  opposing  the  effect  of  the  plate.  When  the  grid  is  negatively 
charged,  it  repels  electrons  back  to  the  filament  and  therefore 
no  grid  current  flows.  Electrons  in  large  numbers  may,  how- 
ever, pass  through  the  spaces  between  the  grid  wires  because  of 


VACUUM  TUBE  AS  RECTIFIER  AND  RELAY       51 

their  high  velocity  and  be  attracted  by  the  plate.  If  the  grid 
potential  is  too  negative  it  will  completely  neutralize  the  effect 
of  the  positive  plate  charge  and  cause  the  plate  current  to  be 


c 


<0 


3 

O 


80 


70 


60 


50 


40 


30 


5   20 


JO 


o- 


60 

Volts 

*y 

^y 

^  / 

<7 

J) 

/  \^ 

7 

-3     -2 


+  6       +7 


-I  0+1+2+3        +4       +5 

Grid    Poten+ials  (arbitrary   units) 

Fig.  16 — Characteristic   curves   of   grid  potentials   and   corresponding   plate 

current  values. 

reduced  to  zero.  This  value  of  negative  grid  potential  is  called 
the  "cut-off"  potential. 

The  external  portion  (part  outside  of  the  tube)  of  the  grid 
circuit  is  connected  at  one  end  to  the  grid  and  at  the  other  to 
the  filament.  Therefore  when  potentials  are  applied  to  the  grid, 
they  are  either  positive  or  negative  with  respect  to  the  filament. 
That  is  to  say,  when  a  higher  potential  is  applied  to  the  grid 
than  to  the  filament  its  potential  is  "positive"  with  respect  to 
the  filament.    The  reverse  is  also,  of  course,  true. 

A  graph  is  shown  in  Fig.   16,  which  pictures  the  effect  of 


52 


A  B  C  OF  VACUUM  TUBES 


various  grid  potentials  upon  plate  current  for  three  different 
values  of  plate  potential,  the  filament  current  being  the  same 
in  all  cases.  It  is  to  be  noted  that  the  variation  of  plate  current 
with  grid  potential  is  not  linear  at  all  times,  but  that  the  "charac- 
teristic" graphs  are  curved  at  their  upper  and  lower  portions. 
This  is  a  characteristic  of  vacuum  tubes  which  is  very  valuable, 
as  will  be  seen  more  clearly  later  on.  The  graph  of  grid  poten- 
tials plotted  against  plate  current  is,  therefore,  called  a  "char- 
acteristic curve." 


Relay  Action 

The  action  of  a  grid  may  be  compared  to  that  of  a  telegraph 
relay,  schematic  circuit  of  which  is  shown  in  Fig.  17.  The 
armature  of  the  relay  is 


Line 


Relay 
Magnet  Coils 


1<— Spring 
'• — o 


Sounder 
^Contacts 


{ 


MS 


.."7 
:---^ 


Relay 


Backstop 
Spring 


Armature 


Local 
Battery 

+ 


local  Circuit 


,_i 


'Pivot 

,  Fig.  17 — Circuits   of  telegraph   relay. 


magnetically  attracted  over  toward  the  poles  of  the  electro- 
magnets when  the  key  in  the  line  is  closed  and  current  flows 
through  the  magnet  coils.    When  the  armature  is  attracted,  a 


VACUUM  TUBE  AS  RECTIFIER  AND  RELAY       53 

contact  is  made  and  a  local  circuit  through  a  battery  and  a  tele- 
graph sounder  is  closed.  The  potential  applied  to  the  terminals 
of  the  magnet  coils  may  be  very  small  but  when  the  contact  is 
closed  a  comparatively  large  current  is  allowed  to  pass  through 
the  sounder  coils  and  operate  the  sounder.  A  relay  is  then  a 
device  which  allows  a  small  cause  to  produce  a  large  effect. 
In  the  case  of  the  vacuum  tube,  the  grid  is  placed  much  closer 
to  the  filament  than  is  the  plate.  Small  potentials  when  applied 
to  the  grid  therefore  have  a  larger  effect  upon  the  plate  current 
than  they  would  if  applied  to  the  plate.  The  vacuum  tube  is, 
then,  a  relay.  Its  grid  is  comparable  to  the  armature  of  the 
telegraph  relay  and  the  plate  circuit  of  the  tube  is  comparable 
to  the  local  sounder  circuit.  The  very  interesting  feature  of  the 
vacuum  tube  is,  however,  that  it  has  no  moving  parts.  It  is  true 
that  the  electrons  move,  but  they  have  no  weight  (are  not  af- 
fected by  gravity)  and  cannot  be  considered  as  parts  of  the 
tube.  As  far  as  can  be  seen,  no  action  takes  place  within  a  tube 
except  the  heating  of  the  filament  to  produce  light. 

Rectification 

In  Fig.  18  a  generator  of  alternating  E.M.F.  is  connected 
into  the  grid  circuit  in  place  of  the  battery  of  Fig.  15.  Refer- 
ring now  to  Fig.  19,  the  normal  potential  of  the  grid  is  assumed 
to  be  the  same  as  that  of  the  filament,  that  is,  it  is  zero  with 
respect  to  the  filament.  A  certain  steady  value  of  plate  current 
then  flows,  depending  upon  the  plate  potential  and  filament 
current.  This  may  be  called  the  "normal"  value  of  plate  cur- 
rent. The  alternating  potentials  applied  to  the  grid  circuit  by 
the  generator  cause  the  grid  to  alternately  become  positive  and 
negative  with  respect  to  the  filament.  When  the  grid  is  positive 
the  plate  current  increases  above  the  normal  value.    When  the 


54 


A  B  C  OF  VACUUM  TUBES 


grid  is  negative  the  plate  current  decreases  below  the  normal. 
There  are  variations  or  alternations  of  plate  current  above  and 
below  this  normal  value  which  are  in  step  with  the  grid  poten- 
tial variations.  Note  particularly,  however,  that  the  increases 
are,  in  this  particular  case,  larger  than  the  decreases.  That  is, 
that  equal  variations  of  grid  potential  cause  unequal  variations 
of  plate  current.   This  being  the  case,  the  average  value  of  the 


Grid 


/\ 

Fila- 
ment 


Generator 


©of Alternating 
E.M.E 


Plate 


•f  QPos. 


,  Plate 
Battery 


JrTegr. 


& 


Current    Indicating 
Device 

Fig.  18— Continuous   variations    of    grid   potentials. 

plate  current  is  at  every  instant  greater  than  the  normal  value. 
If  the  generator  were  started  and  stopped  periodically  this 
average  value  would  rise  when  the  generator  is  running  and 
fall  back  tc  normal  when  the  generator  is  momentarily  stopped. 
There  would  then  be  periodical  increases  and  decreases  of 
average  plate  current  in  step  with  the  starting  and  stopping 
of  the  generator.  As  far  as  this  average  value  is  concerned 
there  appears  to  be  what  is  called  a  "rectification"  of  the 
more  rapid  plate  current  variations.     This  is  "apparent  recti- 


VACUUM  TUBE  AS  RECTIFIER  AND  RELAY 


o;> 


.2 

c 

o 

."H 

b£ 


■*-> 

■i— 

G 
<u 
u 
u 

S3 

o 

+•> 


C 

o 

s 

> 

1. 


(s|iun   X"aej4iqiB)  ^.uajJOQ  aieid 


56 


A  B  C  OF  VACUUM  TUBES 


fication"  of  the  plate  current.  Coincident  with  this  action 
there  is  also  an  actual  rectification  of  the  grid  current. 
That  is,  when  the  grid  receives  a  positive  charge  from  the 
generator  it  attracts  electrons  to  itself  and  a  current  flows  in  the 
grid  circuit.  But  when  the  grid  receives  a  negative  charge  it 
repels  electrons  and  no  current  can  flow  in  the  grid  circuit.  The 
action  of  the  grid  therefore  changes  the  alternating  current 
which  would  otherwise  flow  under  the  influence  of  applied 
alternating  E.M.F.  into  a  pulsating  current.  This  is  actual 
rectification. 

If,  by  means  of  a  grid  battery  (Fig.  20),  there  is  a  certain 
normal  positive  potential  applied  to  the  grid,  the  normal  plate 


Grid 
Battery 


^Generator  of 
(r^j)  A  Item  dh'ng 
V7    E.M.F. 


Fit. 


Pos. 


=EZ  Plate 
=-  Battery 


Battery  —==- 


'O0ff  ■ 


Neg.%^ 


Current  Indicating 
Device. 


Fig.  20 — One    method    of    applying    a    desired    normal    grid    potential. 


current  is  increased  to  a  greater  steady  value.  In  this  case 
the  same  equal  variations  of  grid  potential  produced  by  the 
generator  alternately  increase  and  reduce  the  positive  potential 


VACUUM  TUBE  AS  RECTIFIER  AND  RELAY   57 

on  the  grid.  This  again  causes  unequal  variations  of  plate  cur- 
rent above  and  below  the  new  normal  value,  but  the  decreases 
are  greater  than  the  increases.  The  variations  are,  however, 
still  in  step  with  the  grid  potential  variations.  Since  a  grid  cur- 
rent is  always  flowing,  there  is  no  actual  rectification  of  grid 
current  but  only  an  apparent  rectification.  There  still  is,  never- 
theless, apparent  rectification  of  the  plate  current.  It  is 
interesting  to  note  that  both  the  more  rapid  variations  of  plate 
current  and  the  slower  variations  of  average  plate  current  may 
take  place  in  the  circuit  at  the  same  time  if  the  generator  is 
periodically  started  and  stopped.  Under  favorable  conditions 
currents  of  both  the  higher  and  lower  frequencies  may  flow 
in  the  plate  circuit. 

It  is  a  characteristic  of  vacuum  tubes  that  the  increase  and 
decrease  of  plate  current  with  variations  of  grid  potential  is 
not  linear.  This  has  been  previously  mentioned,  but  it  may  be 
pointed  out  here  that  this  very  characteristic  may  be  made  use 
of  in  operating  the  tube  as  a  rectifier.  Straight  lines  drawn  to 
indicate  values  of  grid  potential  and  plate  current  are  seen,  in 
Fig.  19,  to  cross  each  other  on  the  graph  indicating  the  relation 
between  the  two.  If  two  such  lines  are  drawn  to  indicate  the 
normal  grid  potential  and  the  coincident  normal  plate  current, 
the  point  where  they  cross  on  the  characteristic  curve  may  be 
called  the  "operating  point,"  since  variations  in  both  take  place 
about  this  point.  It  is  obvious,  therefore,  that  the  operating 
point  may  be  shifted  at  will  by  the  application  of  the  required 
normal  grid  potential. 

In  order  to  secure  apparent  rectification  of  plate  current  vari- 
ations it  then  becomes  necessary  to  have  the  operating  point  on 
either  the  upper  or  lower  bend  of  the  characteristic  curve.  It  is 
most  always  brought  to  the  lower  bend  to  avoid  grid  current 
flow  and  very  high  values  of  plate  current  which  add  nothing 


58  A  B  C  OF  VACUUM  TUBES 

to  the  efficiency  of  the  tube,  but  actually  result  in  poorer 
operation. 

With  the  characteristic  curve  of  Fig.  19  a  grid  current  will 
flow  in  the  tube  at  certain  times  because  the  grid  potential  is 
allowed  to  become  positive  periodically  even  though  the  operat- 
ing point  is  on  the  lower  bend  of  the  curve. 

All  tubes,  however,  do  not  have  the  same  characteristics 
and  in  some  cases  it  might  be  necessary  to  apply  a  normal 
negative  potential  to  the  grid  to  bring  the  operating  point  to 
the  lower  bend  of  the  curve.  If,  then,  the  applied  alternating 
potentials  never  exceed  this  value  of  negative  potential,  no  grid 
current  will  flow  at  any  time.  There  is  no  rectification 
of  grid  current,  but  there  is  still  apparent  rectification  of  plate 
current. 

In  the  next  chapter  the  practical  application  of  the  rectify- 
ing action  to  radio  reception  is  brought  out. 


CHAPTER  III 

THE  VACUUM  TUBE  DETECTOR 

The  telephone  receiver — Simple  detection — Detection  with  grid  con- 
denser— Effect  of  gas  in  a  detector  tube — Heterodyne  action  or  the  pro- 
duction of  beats. 

The  Telephone  Receiver 

When  ether  waves  are  produced  at  a  distant  transmitting 
station  and,  in  turn,  cause  oscillating  electric  current  to  flow  in 
a  receiving  antenna,  it  is  necessary  to  provide  some  kind  of  an 
indicator  which  will  make  the  presence  of  these  oscillations 
manifest  to  one  of  the  senses.   It  is  customary  to  translate  these 

Cap  Thready        /Permanent  hard 
steel  magnets 

■Soft  Stee/ 
Pole  Pieces 

■'Binding  Post 


Electromagnet 
Coils 


Soft  Iron 
Diaphragm 


Ordinary  Receiver 

Fig.  21 — Construction   of   a  typical  telephone  receiver. 


oscillations  into  audible  sound  so  that  signals  may  be  perceived 
by  the  sense  of  hearing.  A  telephone  receiver,  the  construction 
of  which  is  shown  in  Fig.  21,  has  two  coils  of  wire,  each 
wound  in  many  layers  around  an  iron  core  to  produce  two 
electro-magnets.  A  metal  diaphragm  is  so  supported  that  it 
may  be  attracted  by  the  magnet  poles  or  released,  depending 
upon  the  strength  of  magnetism  in  the  poles.    An  increase  of 

59 


6o  A  B  C  OF  VACUUM  TUBES 

electric  current  through  the  magnet  windings  causes  the  dia- 
phragm to  be  attracted  and  a  decrease  of  current  causes  it  to  be 
released,  because  the  strength  of  magnetism  is  thereby  in- 
creased and  decreased.  If  the  diaphragm  is  attracted  and  re- 
leased periodically  it  is  caused  to  vibrate,  and  if  the  mechanical 
frequency  of  vibration  (number  of  attractions  and  releases  per 
second)  is  somewhere  between  15  and  15,000  vibrations  per 
second,  the  air  waves  thereby  created  will  produce  audible 
sound  in  the  human  ear.  The  more  rapid  the  vibrations  are,  the 
higher  the  pitch  of  the  sound  which  is  produced.  The  telephone 
receiver  is  a  very  sensitive  indicator  or  translator  and  is  very 
extensively  used  in  radio  work  for  this  purpose. 

Simple  Detection 

In  Fig.  22  there  is  an  antenna  circuit  containing  a  coil  and 
a  condenser,  both  of  which  are  variable  to  provide  for  the 
tuning  of  the  circuit.  The  opposite  terminals  of  the  coil  are 
connected  to  the  grid  and  filament  of  a  vacuum  tube  as  shown. 
Suppose  that  continuous  oscillations  are  present  in  the  an- 
tenna and,  therefore,  flowing  in  the  coil.  If  the  antenna  is  in 
resonance  with  a  transmitting  antenna,  these  oscillations  will 
be  of  maximum  amplitude  and  will  set  up  radio  frequency 
oscillations  of  potential  at  the  coil  terminals,  which  will  also  be 
of  maximum  amplitude.  Now,  the  coil  terminals  are  connected 
to  grid  and  filament  so  that  the  oscillating  potentials  must  be 
applied  to  the  grid  and  filament  of  the  tube.  The  oscillating 
potentials  at  the  coil  terminals  have  now  replaced  the  alternat- 
ing E.M.F.  produced  by  the  generator  of  Fig.  18,  and  their 
frequency  is  very  much  higher  than  the  alternating  E.M.F. 
then  considered.  The  plate  current  variations  now  take  place 
at  radio  frequency  instead  of  at  the  frequency  of  generator 


VACUUM  TUBE  DETECTOR 


61 


E.M.F.  or  potential  variations.  Fig.  19  may  be  referred  to 
again  and  the  operating  point  considered  to  be  on  the  lower 
bend  of  the  curve.  Equal  variations  of  grid  potential  at  the 
radio  frequency  produce  unequal  variations  of  plate  current  at 
radio  frequency.  Now,  radio  frequency  is  always  entirely  be- 
yond the  frequency  range  of  audible  sound,  so  that  if  the  tele- 


Anienna 


Plate 

'  Batfery 


Variable 
Inductance 


Variable 
Capacitance 


telephone  , 
Receiver 


Filament 
Rheostat 


-=-  Grouncf 

Fig.  22 — Simple   detector   circuit. 


phone  receiver  diaphragm  vibrates,  it  does  so  at  a  rate  which 
is  too  high  to  produce  sound.  As  a  matter  of  fact,  however, 
the  diaphragm  does  not  vibrate  at  such  frequency  because  of 
its  weight  and  because  very  little  current  of  radio- frequency 
can  flow  through  the  magnet  windings.  It  must  be  remem- 
bered that  the  reactance  of  a  coil  (or  coils)  increase  with  the 
frequency  and  with  the  insertion  of  an  iron  core.     The  react- 


62  A  B  C  OF  VACUUM  TUBES 

ance  of  an  ordinary  telephone  receiver  winding  is  very  high 
indeed  to  currents  of  radio- frequency.  The  current  that  does 
flow  through  the  receiver  windings  is  the  average  value  of 
direct  current  in  the  plate  circuit.  In  the  case  under  consid- 
eration this  average  current  is  higher  than  the  normal  value 
and  remains  constant  so  long  as  the  amplitudes  of  the  antenna 
oscillations  do  not  vary.  Therefore,  when  unmodified  un- 
damped waves  are  radiated  by  a  transmitting  station  no  sound 
is  produced  in  a  telephone  receiver  at  the  receiving  station  with 
a  simple  detector  circuit. 

Suppose,  however,  that  damped  waves  are  radiated  by  the 
transmitting,  station.  In  this  case  it  will  be  remembered  that 
there  are  groups  (or  trains)  of  oscillations  produced  in  the  re- 
ceiving antenna,  each  composed  of  radio  frequency  oscillations 
whose  amplitudes  decay  from  a  maximum  value  to  zero  peri- 
odically. The  grid  and  filament  circuit  of  Fig.  22  then  being 
still  connected  across  the  antenna  coil,  radio-frequency  potential 
variations  are  applied  to  the  grid,  whose  amplitudes  decay 
from  a  maximum  to  zero  during  each  group  of  oscillations,  as 
shown  in  Fig.  23.  As  also  shown  in  the  graph  of  this  figure, 
the  radio- frequency  plate  current  variations  also  decrease  in 
amplitude  during  each  group  or  train  of  oscillations  and  there 
is  a  variation  in  the  average  plate  current  which  rises  and  falls 
once  for  each  oscillation  train.  If  the  frequency  of  the  oscil- 
lation trains  is  within  the  limits  of  audibility  (15  to  15,000 
per  second)  the  frequency  of  the  variations  of  average  plate 
current  is  also  an  audible  frequency  or,  as  it  is  called,  an  "audio- 
frequency." Current  variations  of  such  comparatively  low  fre- 
quency pass  through  the  receiver  windings  and  cause  the  dia- 
phragm to  vibrate  and  to  produce  sound  waves  of  the  same 
frequency  which,  being  audible,  are  heard  by  the  human  ear. 
The  sound  heard  depends  then  upon  the  frequency  of  the  oscil- 


VACUUM  TUBE  DETECTOR 


63 


o 

-+- 

CD 

a. 


Norma/ 
Plate   -a 
Current- 


Zero 


Radio 
Frequency-.^  — 


Frequency  of 
"Oscillation 

Trains  "same 
as  Wave  Train 
Frequency. 
(Only  One 

Train  Shown) 


Fig.  23 — Rectification   effect   in   plate   current   with   damped   grid   potential 

variations. 


64  A  B  C  OF  VACUUM  TUBES 

lation  trains  and  increases  in  pitch  with  that  frequency.  Sup- 
pose a  case  in  point  is  considered.  There  is  a  transmitter  at  a 
distant  station  which  creates  in  the  transmitting  antenna  oscil- 
lations whose  frequency  is  iooo  per  second.  The  transmitter 
could  be  a  500  cycle  synchronous  rotary  gap  or  quenched  gap 
spark  transmitter.  Ether  wave  trains  are  set  up  whose  fre- 
quency is  also  1000.  These  ether  waves  cause  trains  of  oscil- 
lations in  the  receiving  antenna,  variations  of  average  plate  cur- 
rent, receiver  diaphragm  vibrations  and,  finally,  sound  waves, 
all  of  the  some  frequency,  1000  per  second.  If  the  distant 
transmitter  were  a  240  cycle  set,  ether  wave  trains  of  480  per 
second  would  be  created  and  the  frequency  of  the  sound  waves 
produced  by  the  receiver  diaphragm  would  be  480  per  second. 
The  pitch  of  the  tone  would  be  higher  in  the  first  case  than  in  the 
second,  although  both  tones  would  be  musical.  Damped  oscil- 
lations, being  modified  radio  frequency  oscillations,  produce 
audible  sound  in  a  telephone  receiver. 

If  the  undamped  oscillations  generated  by  a  transmitter  are 
modified  by  auxiliary  apparatus  in  such  a  manner  as  to  vary  the 
amplitudes  of  the  radio- frequency  oscillations  at  an  audio- 
frequency rate  (frequency  with  the  limits  of  audible  sound), 
air  waves  of  the  same  audible  frequency  will  be  produced  by 
the  receiver  diaphragm.  The  radio- frequency  oscillations  are 
molded  into  groups  and  that  group  frequency  is  selected  which 
will  give  the  most  pleasing  pitch  of  tune  in  the  telephone  re- 
ceiver. Such  a  process  of  molding  is  called  "modulation." 
Fig.  24  illustrates  the  effect  of  modulated  continuous  oscilla- 
tions in  a  simple  detector  circuit.  The  group  frequency  is 
maintained  at  a  constant  value,  usually,  so  that  the  tone  does 
not  change  at  any  time.  Different  transmitting  stations  may, 
however,  select  different  group  frequencies  and  therefore  pro- 
duce tones  in  a  receiver  which  differ  from  each  other.   A  trans- 


VACUUM  TUBE  DETECTOR 


65 


mitting  station  can  then  often  be  identified  by  its  tone  fre- 
quency. 

A  radio-telephone  transmitter  must  use  a  generator  of  con- 
tinuous radio  frequency  oscillations  but,  in  this  case,  the  radio 

1  '  ogfaSS? 


c 
o 

Q. 


/  Radio  Frequency  Plate 
Current  Variations 


^ — Normal  Grid  Potential 

—Audio  Frequency  Grid 
Potential  Variations. 
(Only  one  Cycle  shown.) 

"■Radio  Frequency  Grid 
Potential  Variations. 


Fig.  24 — Detection    of    modulated    continuous    oscillations    at    a    constant 

group   frequency. 

frequency  current  amplitudes  are  not  always  varied  at  the  same 
audible  frequency  as  is  usually  the  case  with  modulation  for 
telegraphic  purposes.  The  frequency  of  the  sound  waves  cre- 
ated by  the  human  voice  averages  around  800  per  second,  but 
constantly  increases  and  decreases  with  the  pitch  of  tone.  Every 
change  in  inflection  of  the  speaking  voice  and  every  change  in 


66  A  B  C  OF  VACUUM  TUBES 

tone  of  the  singing  voice  means  a  change  in  the  frequency  of 
the  air  waves  created.  In  the  case  of  music  produced  by  various 
instruments,  every  change  in  tone  also  means  a  change  in  air 
wave  frequency.  In  the  operation  of  a  radio-telephone  trans- 
mitter, devices  are  provided  which  will  cause  the  originally 
generated  undamped  radio  frequency  oscillations  to  be  molded 
or  modulated  constantly  in  amplitude  at  constantly  varying  tone 
frequency.  The  constant  changes  in  tone  (group)  frequency 
therefore  produced  in  the  receiving  antenna  cause  constantly 
varying  changes  in  the  current  flowing  through  a  telephone  re- 
ceiver of  the  simple  detector  circuit.  The  result  is,  of  course, 
air  waves  and  sound  created  by  the  receiver  diaphragm  of  con- 
stantly changing  frequency  in  step  with  the  frequency  of  the 
sound  waves  acting  upon  the  distant  transmitter.  Fig.  25  gives 
an  idea  of  how  this  is  accomplished  in  the  receiving  circuits. 
In  all  of  the  above  considerations  it  is,  of  course,  understood 
that  the  receiving  antenna  must  be  tuned  to  the  radio  fre- 
quency oscillations  no  matter  what  the  group  or  tone  frequency 
may  be. 

Detection  with  Grid  Condenser 

In  the  case  of  simple  detection  there  may  be  actual  or  appar- 
ent rectification  of  grid  current,  depending  upon  the  normal 
grid  potential.  If  a  small  condenser  is  connected  into  the  grid 
circuit  close  to  the  grid,  however,  the  rectification  of  grid  cur- 
rent is  actual.  There  is  also  apparent  rectification  of  the 
plate  current  variations.  The  mode  of  functioning  is  some- 
what different,  however,  when  a  grid  condenser  is  used. 

Assume  that,  due  to  resonance  with  a  transmitting  antenna, 
there  are  damped  radio  frequency  oscillations  of  maximum 
possible  amplitudes  induced  in  the  receiving  antenna      Radio 


VACUUM  TUBE  DETECTOR 


67 


7ero 


Radio 
Frequency 
Grid  Potential 
Variations — \ 


N Radio 

Frequency 
Plate  Current 

Variations 


Fig.  25 — Detection  of  voice  modulated  continuous  oscillations  at  a  varying 

group  frequency. 


68  A  B  C  OF  VACUUM  TUBES 

frequency  alternating  potentials  are  applied  to  the  grid  through 
the  grid  condenser.  When  the  grid  receives  a  positive  charge 
from  the  circuit  it  attracts  electrons  to  itself,  a  grid  current 
flows  and  the  plate  current  is  momentarily  increased,  since  the 
operating  point  is  now  assumed  to  be  on  the  straight  portion 
of  the  curve.  (Fig.  26).  The  grid  then  receives  a  negative 
charge,  repels  electrons,  no  grid  current  can  flow  and  the  plate 
current  is  reduced.  But,  when  the  grid  was  positive  and  elec- 
trons were  attracted  to  it  these  electrons  were  trapped  on  the  grid 
because  of  the  "blocking"  action  of  the  grid  condenser.  When, 
during  succeeding  alternations  of  the  applied  potential,  the  grid 
receives  a  positive  charge  more  electrons  are  attracted  to  the 
grid  and  are  trapped.  During  one  group  of  oscillations  then, 
the  grid  accumulates  electrons,  its  negative  potential  increases 
and  the  average  plate  current  decreases.  (Electrons  are 
negative  charges.)  It  may  be  pointed  out  here  that  the 
normal  potential  of  the  grid  with  respect  to  the  filament  is 
always  zero.  During  a  group  of  oscillations  the  negative 
charge  on  the  grid  is  built  up  to  a  comparatively  large 
value  and,  unless  the  charge  leaks  off  of  the  grid,  the  grid 
potential  will  not  be  zero  at  the  beginning  of  the  next  group 
of  oscillations.  During  the  group  of  oscillations  just  con- 
sidered the  operating  point  has  slid  down  the  characteristic 
curve.  If  this  negative  grid  charge  does  not  entirely  leak 
off,  the  next  group  of  oscillations  will  cause  the  negative 
grid  potential  to  increase  and  the  operating  point  to  slide 
still  further  down  the  curve.  It  is  obvious  that  the  cut-off 
grid  potential  might  be  reached  and  the  plate  current  stopped 
entirely.  When  this  happens  the  tube  is  said  to  be  "blocked" 
or  "choked."  It  is  paralyzed  until  the  grid  charge  is  allowed 
to  leak  off,  for  example  by  placing  the  ringers  on  the  grid 
terminal.     It  is  quite  necessary,  therefore,  to  provide  a  path 


VACUUM  TUBE  DETECTOR 


69 


One  Train  of 
Radio  Frequency 
Antenna  Oscillations 


Fig.  26 — Rectification    or    detection    of    damped    oscillations    with    a    grid 

condenser. 


70  ABC  OF  VACUUM  TUBES 

through  which  the  negative  charge  may  leak  when  it  becomes 
large,  so  that  the  grid  potential  may  be  returned  to  zero 
and  the  plate  current  to  normal  in  time  for  the  next  group. 
This  may  be  accomplished  by  connecting  a  resistance  called 
a  "grid  leak  resistance"  across  the  grid  condenser  terminals 
or  directly  between  the  grid  and  the  filament.  The  value  of 
resistance  must  be  high  enough  to  prevent  any  great  flow  of 
current  through  it  until  the  maximum  charge  has  accumulated 
upon  the  grid.  It  should  not  be  too  high,  however,  because  the 
charge  would  not  then  leak  off  quickly  enough,  but  might  accu- 
mulate until  it  leaks  off  through  the  glass  walls  of  the  tube,  the 
dielectric  of  the  grid  condenser  or  the  vacuuous  space  between 
filament  and  grid.  This  might  cause  a  thumping  noise  in  the 
telephone  receiver. 

In  the  next  section  tubes  containing  gas  are  described.  If 
such  a  tube  is  used  as  a  detector  the  negative  grid  charge  may 
leak  from  the  grid  to  the  filament  because  of  the  comparatively 
good  conducting  path  then  offered.  If  the  gas  content  of  the 
tube  is  high  enough  no  grid  leak  is  necessary.  Modern  gas 
content  tubes,  however,  usually  require  a  grid  leak  resistance 
when  used  with  a  grid  condenser. 

In  Chapter  V  various  practical  circuits  are  described  which 
show  the  schematic  connections  of  grid  condensers  and  grid 
leaks.  No  grid  battery  is  ever  needed  with  a  grid  condenser. 
The  rectification  of  plate  current  oscillations  does  not  depend 
entirely  upon  the  location  of  the  operating  point  because  it 
is  the  cumulative  effect  of  the  negative  grid  charge  which 
causes  the  plate  current  decrease  during  each  group  of  oscil- 
lations. As  a  matter  of  fact,  however,  it  is  desirable  to 
have  the  normal  operating  point  on  the  straight  portion 
of  the  curve  so  that  the  decrease  of  grid  potential  caused 
by  accumulation  of  negative  charge  will  produce  the  greatest 


VACUUM  TUBE  DETECTOR  71 

possible  change  in  plate  current.     Reference  to  Fig.  26  will 
make  all  these  points  more  clear. 

The  effect  of  the  grid  condenser  does  not  change  the  relation 
between  the  group  frequency  of  the  antenna  oscillations  and  the 
group  frequency  of  the  plate  current  variations.  The  latter  is 
still  the  same  as  the  former  and  the  frequency  of  air  waves 
(pitch  of  sound)  is  still  the  same  as  the  group  frequency  of 
oscillations  in  the  antenna  circuit.  The  detector  with  grid  con- 
denser may  be  used  for  the  reception  of  damped  waves,  modu- 
lated undamped  waves  for  telegraphic  purposes  or  voice 
modulated  undamped  waves  as  in  radio-telephony.  Later  on  it 
will  be  shown  how  straight  undamped  waves  may  also  be  de- 
tected by  modifying  the  radio- frequency  oscillations  in  the 
receiving  circuit. 

Effect  of  Gas  in  a  Detector  Tube 

Under  "Tube  Construction"  in  the  preceding  chapter  it  was 
stated  that  some  tubes,  called  "soft"  tubes,  contain  a  small 
amount  of  gas.  This  gas  is  rarefied,  of  course,  since  the  vacuum 
within  the  tube  is  still  comparatively  high,  although  not  as  per- 
fect as  it  might  be  made.  Electrons  are  not  matter  in  any  shape 
or  form,  but  gas  is  most  certainly  a  form  of  matter.  Therefore 
if  there  is  gas  within  a  tube,  the  tube  space  is  not  absolutely 
devoid  of  matter,  except  for  the  electrodes,  but  has  matter  be- 
tween the  filament,  grid  and  plate.  Its  action  also  cannot, 
therefore,  be  exactly  like  a  very  high  vacuum,  or  "hard,"  tube. 

The  smallest  possible  particle  of  gas  is  called  an  "atom."  It 
is  too  small  to  be  seen  but,  nevertheless,  has  weight  because  it 
can  be  acted  upon  by  gravity.  Electrons  do  not  have  weight 
because  they  cannot  be  acted  upon  by  gravity.  Each  atom  of 
gas  has  a  central  nucleus  which  carries  a  positive  charge  of  elec- 


72  A  B  C  OF  VACUUM  TUBES 

tricity.  This  nucleus  is  surrounded  by  electrons  (negative 
charges)  so  that,  normally,  the  sum  of  all  the  negative 
charges  of  the  electrons  equals  the  positive  charge  of  the 
central  nucleus.  If  an  electron  projected  at  high  velocity 
from  a  filament  collides  with  an  atom  of  gas,  it  may  very 
easily  cause  one  or  more  electrons  to  be  torn  away  from 
the  atom.  When  such  a  thing  occurs,  the  positive  charge 
of  the  atom  over-balances  its  remaining  negative  charges 
and  it  acts  like  a  positive  charge  of  electricity.  In  this 
condition  it  is  called  an  "ion."  That  is,  an  atom  is  known  as  an 
"ion"  after  it  has  lost  one  or  more  electrons.  It  is  quite  con- 
ceivable that  if  there  are  thousands  of  electrons  projected  from 
the  filament  per  second,  all  at  high  velocity,  many  collisions 
might  take  place  between  them  and  the  gas  atoms.  Many  ions 
would  then  be  created.  Such  action  is  called  "ionization  by  col- 
lision." Now,  under  the  influence  of  a  positively  charged  plate, 
the  electrons  emitted  by  the  filament  and  those  set  free  by 
collision  move*  toward  the  plate  and  are  attracted  to  it  at  a  rate 
depending  upon  its  potential.  The  ions  are  repelled  by  the  plate 
toward  the  filament.  Suppose  that  electrons  are  not  projected 
in  sufficient  numbers  per  second  from  the  filament  to  equal  the 
rate  of  attraction  of  the  plate.  If  additional  electrons  are  pro- 
duced by  collision,  they  may  make  up  the  deficiency  and  cause 
the  plate  current  to  be  increased  without  the  increase  of  filament 
temperature.  Care  must  be  taken,  however,  to  keep  the  plate 
potential  below  the  value  which  causes  too  large  plate  current. 
When  too  much  plate  current  flows  there  will  be  a  visible  blue 
glow  inside  the  tube  and  the  plate  current  will  not  be  appreci- 
ably affected  by  the  grid  potential  variations.  The  result  is  very 
erratic  action  of  the  tube  and  a  decrease  in  volume  of  sound 
from  the  telephone  receiver.  The  "soft"  tube  is  more  sensitive 
as  a  detector  than  the  "hard"  tube,  but  it  has  its  disadvantages. 


VACUUM  TUBE  DETECTOR 


73 


The  most  marked  disadvantage  is  probably  the  critical  adjust- 
ment of  filament  temperature  and  plate  potential  necessary  to 
satisfactory  operation.  Another  is  the  shortened  life  of  the 
tube  caused  by  the  bombardment  by  the  comparatively  heavy 
ions  which  are  driven  against  it  when  they  are  repelled  by  the 
plate. 

Heterodyne  Action,  or  the  Production  of  Beats 

It  has  been  pointed  out  that  unmodulated  (unmodified)  un- 
damped radio  frequency  oscillations  will  not  produce  sound  in 


1,000-  Telephone  Current--' 
Fig.  27 — The  principle   of   heterodyne   action. 

a  telephone  receiver.  If,  however,  oscillations  of  a  different 
frequency  are  generated  locally  and  forced  to  flow  in  an  antenna 
circuit  there  is  an  interaction  between  the  two  frequencies  which 
produces  oscillations  of  a  third  frequency  equal  to  the  numeri- 


74 


A  B  C  OF  VACUUM  TUBES 


cal  difference  between  the  other  two.  The  third  frequency  must 
then,  of  course,  be  lower  than  either  of  the  other  two.  This 
action  is  called  ''heterodyne  action"  and  the  oscillations  of  the 
third  and  lower  frequency  are  called  "beats."  The  curves  of 
Fig.  2.J  show  this  graphically.  There  are,  in  this  case,  oscilla- 
tions induced  in  the  antenna  circuit  (by  a  distant  transmitter) 
whose  frequency  is  100,000  cycles  per  second  and  oscillations 


V 


Plate 
Battery 


Ffl. 


Battery  - 


Oscillation 
Generator 


Filament 
Rheostat 


7~\ 


Fig.  28 — Schematic  circuit  for  the  production  of  beats. 


produced  by  a  local  oscillation  generator  whose  frequency  is 
101,000  cycles  per  second.  Both  are  radio  frequencies  and 
neither  by  itself  produces  any  audible  response  in  the  telephone 
receiver.  Now,  the  local  oscillations  are  forced  to  flow  in  the 
antenna  circuit  although  the  latter  is  not  tuned  to  them.  This 
is  because  of  a  strong  inducing  action  of  the  local  generator 
upon  the  antenna  circuit.   The  amplitude  of  the  forced  oscilla- 


VACUUM  TUBE  DETECTOR  75 

tions  (of  101,000  cycle  frequency)  in  the  antenna  circuit  is  not 
maximum,  but  that  makes  no  difference.  The  frequency  of  the 
third  set  of  oscillations  in  the  antenna  circuit  is  1000  cycles 
per  second  (within  the  limits  of  audible  sound)  and  will 
cause  the  average  plate  current  to  vary  or  pulsate  1000  times 
per  second  and  the  telephone  receiver  diaphragm  to  vibrate  at 
the  same  frequency.  The  sound  waves  produced  are,  then,, 
at  the  rate  of  1000  per  second  and  the  same  tone  is  heard  as 
would  be  if  the  transmitter  at  the  distant  station  were  a  500 
cycle  spark  set.  In  this  manner  the  undamped  waves  are 
modified  by  heterodyning  at  the  receiving  station  and  made 
to  produce  an  audible  response  in  the  telephone  receiver. 

Various  schematic  circuits  are  illustrated  in  a  following 
chapter,  which  show  how  connections  may  be  made  to  produce 
this  heterodyne  action.  The  local  oscillations  may  be  generated 
by  an  entirely  separate  generator,  as  in  Fig.  28,  or  the  detector 
circuit  may  be  slightly  changed  so  that  it  acts  as  an  oscillation 
generator  at  the  same  time  that  it  acts  as  a  detector. 


CHAPTER  IV 

THE  VACUUM  TUBE  AMPLIFIER 

General  characteristics — Audio  frequency  amplification — Radio  fre- 
quency amplification — Radio  frequency  regenerative  amplification — Auto- 
dyne  production  of  beats. 

General  Characteristics 

Because  of  the  relay  action  of  a  tube,  a  certain  amount  of 
amplification  takes  place  even  when  the  tube  is  functioning  as  a 
detector.  Amplification  may  be  said  to  be  an  inherent  property 
of  all  vacuum  tubes. 

If  a  steady  potential  is  applied  to  the  grid  which  brings  the 
operating  point  to  a  position  on  the  straight  portion  of  the 
characteristic  curve,  equal  variations  of  grid  potential  will 
cause  equal  changes  of  plate  current.  No  distortion  of  plate 
current  is  then  caused,  even  with  damped  oscillations,  and  its 
variations  are  not  only  in  step  with  the  antenna  oscillations  but 
its  amplitudes  are  proportional  to  the  amplitudes  of  antenna 
oscillations  at  every  instant.     See  Figs.  29  (a)  and  (b). 

If  radio-telegraph  signals  only  are  received,  distortion  of  the 
oscillating  plate  current  is  not  such  a  serious  drawback.  But 
when  radio-telephone  speech  and  music  are  received  it  is  impera- 
tive that  no  distortion  takes  place  or  the  sounds  heard  may  not 
be  accurate  reproductions  of  the  sounds  at  the  transmitting  sta- 
tion. They  may,  in  fact,  be  so  greatly  distorted  that  they  are 
extremely  difficult  to  understand  or  absolutely  unintelligible. 
An  ideal  amplifier  is,  then,  one  in  which  the  antenna  current  is 
amplified  without  distortion  regardless  of  the  combination  of 
frequencies  involved. 

76 


VACUUM  TUBE  AMPLIFIER 


77 


By  this  time  it  has  probably  become  self-evident  that  the 
volume  of  sound  produced  in  a  telephone  receiver  depends  upon 
the  amplitudes  of  the  diaphragm  vibrations  back  and  forth. 


y  Equal  Grid 
?     Potential 
Variations 


Fig.  29  (a) — Amplification    of    continuous    oscillations. 


These  amplitudes  in  turn  depend  upon  the  amplitudes  of  the 
audio- frequency  plate  current  variations  passing  through  the 
receiver  magnet-coils.  The  coils  smooth  out  the  variations 
somewhat,  but  their  amplitudes  depend  nevertheless  upon  the 
amplitudes  of  the  oscillations  in  the  antenna  circuit.  Because 
of  inherent  amplification  these  audio- frequency  current  ampli- 


78 


A  B  C  OF  VACUUM  TUBES 


tudes  in  the  plate  circuit  are  usually  larger  than  those  in  the 
antenna.    They  may  not,  however,  be  large  enough  to  create  the 


Damped 
6  rid  Pofenfiaf 
Variations 


Fig.  29  (b) — Amplification    of    damped    oscillations. 


desired  amplitudes  of  sound  waves  and  therefore  the  volume  of 
sound  from  the  telephone  receiver.  Amplification  must  then 
be  increased  in  some  manner. 


VACUUM  TUBE  AMPLIFIER  79 

Amplification  Factor 

It  has  been  stated  that  if  the  filament  current  and  plate  po- 
tential are  kept  constant,  the  plate  current  varies  with  the  grid 
potential.  It  is  also  true  that  if  both  filament  current  and  grid 
potential  are  kept  constant,  the  plate  current  varies  with  the 
plate  potential.  There  are  then  two  possible  ways  to  vary  the 
plate  current  when  the  filament  current  is  constant.  But  the 
reason  the  potential  variations  due  to  signals  are  applied  to  the 
grid  rather  than  to  the  plate  is  that  they  have  greater  effect  upon 
the  plate  current  in  the  former  case  than  in  the  latter.  There 
would  otherwise  be  no  object  in  having  a  grid  electrode.  The 
ratio  of  plate  potential  variation  to  grid  potential  variation  re- 
quired to  produce  any  given  change  in  plate  current  is  called  the 
"voltage  amplification  factor."  For  example,  if  a  certain 
increase  in  grid  potential  will  produce  a  certain  increase  in 
plate  current  and  it  takes  an  increase  of  plate  potential  six  times 
that  of  grid  potential  to  produce  the  same  increase  of  plate 
current,  the  voltage  amplification  factor  is  six. 

The  value  of  any  given  vacuum  tube  as  an  amplifier  depends 
upon  this  amplification  factor.  In  general,  all  other  conditions 
being  equal,  the  amplification  factor  of  a  tube  depends  upon  two 
things.  The  first  is  the  relation  between  the  distance  of  the 
plate  from  the  filament  and  the  distance  from  the  grid  to  fila- 
ment. That  is,  with  a  given  distance  between  plate  and  filament, 
the  closer  the  grid  is  to  the  filament  the  greater  this  amplifica- 
tion factor  will  be.  The  second  is  the  spacing  between  the  grid 
wires  (or  distance  between  turns).  The  amplification  factor 
increases  with  a  decrease  of  spacing  and  vice  versa.  Tubes  may 
thus  be  compared  with  each  other  and  their  relative  values  as 
amplifiers  roughly  judged. 

With  any  given  tube,  the  amplification  factor  also  depends 


80  A  B  C  OF  VACUUM  TUBES 

to  some  extent  upon  the  plate  and  grid  potentials.  It  cannot, 
therefore,  be  considered  as  an  actual  constant.  If,  however, 
only  the  straight  portions  of  characteristic  curves  are  consid- 
ered the  effect  of  plate  and  grid  potentials  upon  amplification 
constant  may  be  ignored. 

The  value  of  a  tube  as  an  amplifier  also  depends  upon  the 
degree  of  vacuum  and  the  very  "hard"  tubes  are  considered  far 
superior  to  the  "soft"  tubes  for  amplification  purposes. 

Now,  the  slope  of  the  grid-potential,  plate-current  curve  de- 
pends upon  the  amplification  factor,  other  things  being  equal. 
If  this  characteristic  curve  for  one  tube  is  steeper  than  that  for 
another,  grid  potential  variations  in  the  first  tube  will  produce 
larger  plate  current  variations  than  will  be  produced  in  the 
second  tube  by  the  same  grid  potential  variations.  This  may  be 
seen  by  comparing  Fig.  30  with  Fig.  29  (a).  In  the  case  of  an 
amplifier  tube  it  is  only  the  straight  portion  of  any  characteris- 
tic curve  which  is  of  interest,  since  operation  on  a  bend  of  the 
curve  would  result  in  unsymmetrical  variations  of  plate  current. 

Audio  Frequency  Amplification 

If  it  is  desired  to  amplify  the  audio- frequency  current  in  the 
plate  circuit  of  a  detector  tube,  the  primary  of  a  small  closed 
core  transformer  may  be  connected  between  the  plate  and  the 
positive  terminal  of  the  plate  battery.  The  secondary  of  the 
transformer  is  then  connected  into  the  grid  circuit  of  another 
tube  and  the  normal  potential  on  the  grid  of  this  second  tube 
is  so  adjusted  that  its  operating  point  is  on  the  straight  portion 
of  its  characteristic  curve.  Usually  a  certain  amount  of  steady 
negative  potential  must  be  applied  to  the  grid  of  this  amplifier 
tube  to  accomplish  this  result.  This  may,  of  course,  be  done  by 
inserting  a  grid  battery  of  proper  voltage  into  the  grid  circuit 


VACUUM  TUBE  AMPLIFIER 


81 


and   connecting   the   negative   battery   terminal    to    the    grid. 
Another  and  better  method  is  to  include  a  portion  of  the  fila- 


100 
90 
80 
70 

+.-60 

c 

I  50 
o 


40 
30 
20 
10 


v'^/ 

P/<«fe  Potential 

and  Filament 
Current  Constant 

Opt 

>rat/ht 

7 

\ 

v 

.___. 

.___ 

Po/h'i 

t. 

P/afe  &///< 

ent 

s 

Norm 

il  PI  a 

te   Cut 

i 

rent  *a 

/ 
/ 

/ 

/ 

■*-. 

/ 
/ 

/ 

t. — , — i 

■fc 



-A/_. 



_\Z_ 



'-■ — 

l<3 

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< 

6      -5       -4       - 
Gr 

3       - 
id     P 

2       - 
orent 

1        Q      +1       +2+3      +4      +5      +6 
ial 

5 

Sr/i/  Pofentia/ 

^ 

> 

~~ 

^ 

Fig.  30 — Amplification   of    continuous    oscillations 


ment  rheostat  resistance  in  the  grid  circuit  as  shown  in  Fig.  3 1 . 
This  places  a  negative  potential  upon  the  grid  which  is  equal 
to  the  potential  difference  between  the  points  "X"  and  "Y." 


82 


A  B  C  OF  VACUUM  TUBES 


The  audiofrequency  variations  of  plate  current  in  the  detec- 
tor tube  now  cause  grid  potential  variations  in  the  amplifier 
tube  which  are  larger  in  amplitude  than  the  grid  potential  vari- 


Transformer 


Grid-, 


Plate 


To  Plate 
Circuit  of 
DetectorTube 


u 


Amplif  ier\lube 


JL' 


r 


Filament  ■? %4-*/s 
Rheostat'' 

Filament       ) 
Battery'' 


•="  Plate 
—   Battery 


-© 


Telephone. 
Receiver 


Fig.  31 — Customary    method    of    placing    a    normal    negative    potential    on 
the    grid    of    an    amplifier    tube. 


ations  applied  to  the  detector  tube  by  the  antenna  oscillations. 
These  variations  of  amplifier  grid  potential  will  be  at  die 
audible  frequency  rate  because  radio  frequency  current  vari- 
ations cannot  readily  flow  in  the  detector  plate  circuit  due  to 
the  high  reactance  of  the  transformer  primary.  Audio- 
frequency currents  will  then  flow  in  the  plate  circuit  of  the 
amplifier  tube  and  through  the  telephone  receiver.  The  receiver 
diaphragm  will  vibrate  with  greater  amplitude  because  the 
current  variations  are  of  magnified  amplitude  and,  as  a  final 
result,  the  sound  heard  in  the  telephone  receiver  is  louder.  This 
can  easily  be  verified  by  plugging  a  telephone  receiver  into  the 
jack  of  the  detector  circuit  and  then  into  the  jack  of  the  first 
stage  of  an  audio- frequency  amplifier. 

If  still  further  increase  in  audibility  (or  volume  of  sound)  is 
required  one  or  more  "stages"  of  amplification  may  be  used  in 
the  same  manner.  Such  amplification  is  referred  to  as  "cascade 
amplification."  Usually  two  stages  of  audio  frequency  ampli- 
fication  (two  amplifier  tubes  in  cascade  connection)   are  the 


VACUUM  TUBE  AMPLIFIER  83 

limit,  although  if  care  is  taken  three  stages  may  sometimes  be 
managed. 

The  signals  must,  of  course,  be  put  through  a  detector  tube 
and  rectified  before  they  are  applied  to  an  audio- frequency 
amplifier.  With  cascade  amplification  sufficient  current  may 
frequently  be  secured  in  the  plate  circuit  of  the  last  tube  to 
operate  a  relay  or  a  device  known  as  a  "loud  speaker."  If  the 
relay  is  used,  telegraph  signals  may  be  sent  over  a  land  wire 
from  the  radio  receiving  station  to  a  distant  office  where  an- 
other relay  opens  and  closes  a  local  sounder  circuit.  If  the  loud 
speaker  is  used  both  radio  telegraph  signals  and  radio-telephone 
speech  and  music  may  be  reproduced  with  sufficient  volume  to 
be  heard  considerable  distances  away  from  the  instruments. 

Radio  Frequency  Amplification 

The  amplitudes  of  the  grid  potential  variations  in  any  tube 
control  the  audio- frequency  variations  oi  average  plate  current. 
These  grid  potential  variations  of  course  depend  upon  the  am- 
plitudes of  the  antenna  oscillations.  If  the  antenna  oscillations 
are  weak,  that  is,  if  the  signal  is  weak,  the  grid  potential  vari- 
ations are  also  weak  (of  small  amplitude)  and  a  detector  tube 
may  not  be  made  to  function  propertly  and  possibly  not  at  all. 
This  is  because  the  sensitiveness  of  a  detector  depends  upon 
the  square  of  the  potentials  applied  to  the  grid  by  the  signal 
current.  For  example,  if  a  certain  voltage  applied  to  the  grid 
produces  a  certain  change  in  plate  current,  twice  the  applied 
voltage  will  produce  four  times  the  change  in  plate  current. 
It  is  obvious  that  the  amplitudes  of  the  antenna  oscillations 
might  at  times  be  too  small  to  operate  the  detector  tube.  In  this 
case  there  would  be  no  amplification  of  the  very  weak  signal  by 
means  of  audio- frequency  amplification  because  the  signal  can 
not  operate  the  detector  in  the  first  place. 


84 


A  B  C  OF  VACUUM  TUBES 


When  signals  are  very  weak  it  is  then  of  very  great  advan- 
tage to  amplify  them  before  they  are  rectified.  That  is,  to  am- 
plify the  antenna  oscillations  until  the  potential  variations  are 
high  enough  to  operate  a  detector  tube  to  good  advantage.  To 
do  this  it  is  necessary  to  amplify  radio  frequency  oscillations 
before  rectification. 

The  circuit  shown  in  Fig.  32  may  be  referred  to.  In  this 
circuit  there  is  resistance  inserted  in  the  plate  circuit  of  the  first 


'Antenna 


Filament 


Plate 


Grid, 


Variable 
Inductance\ 


Variable  / 

Capacitance 


V\ 


Ampli 


fier 


w. 


Plate 
Battery 

1 


-T,        Coupling 

lube        9p.<k4-nnt 


Resistance'- 


Grid 
Leak , 


Fit 
RheoJ 


y* 


"*■   To  Grid  and 
Filament 
of  Detector 
Tube 


Ft  I 


J  ^  —  Battery 


-=—  Ground 

Fig.  32 — Single    stage   of    radio-frequency   amplification   using   a   coupling 

resistance. 


or  radio- frequency  amplifier  tube.  Due  to  inherent  amplifica- 
tion, the  plate  current  variations  in  this  first  tube  are  greater 
in  amplitude  than  the  antenna  oscillations.  If  the  coupling 
resistance  is  quite  large,  amplified  potential  variations  are 
applied  to  the  second  or  detector  tube.  Let  it  be  assumed  that 
these  amplified  potentials  are  sufficient  to  operate  the  detector 
tube  to  good  advantage.  The  rectified  plate  current  variations 
will  then  be  of  audio- frequency  and  the  telephone  receiver  will 
function  providing  the  antenna  oscillations  of  radio  frequency 
are  modified  at  an  audio-frequency  rate. 

If  one  stage  of  radio-frequency  amplification  is  not  enough, 


VACUUM  TUBE  AMPLIFIER 


85 


more  amplifier  tubes  may  be  coupled  together  in  the  same 
manner  until  sufficient  potential  is  produced  to  properly  operate 
the  detector  tube.     This  is  again  called  "cascade"  amplification, 

» 

but  this  time  the  amplification  is  of  radio- frequency  only. 
There  are  as  many  "stages"  of  amplification,  of  course,  as 
there  are  amplifier  tubes. 

Radio-Frequency  Regenerative  Amplification 

Referring  to  Fig.  33,  there  is  a  coil   (air  core)   connected 
into  the  plate  circuit  of  a  detector  tube  and  so  placed,  in  relation 


Grid 
Leak 


.-Grid 
Condenser 


Variable 
Induct- 
ance    L 


Plate 
Coil 


+t 


Plate' 


Plate 
Bat- 
tery 


Telephone 
~—  Battery  ^Receiver 


By- Passing 
=  Conden- 
ser 


Fig.  33 — Showing   how   energy   may  be    fed   back    from    the   plate    circuit 
to  the  grid  circuit  to  produce  regeneration. 


to  the  grid  coil,  that  a  radio- frequency  oscillating  current  in 
the  plate  circuit  will  induce  a  radio- frequency  E.M.F.  in  the 
circuit  composed  of  the  grid  coil  and  the  condenser  connected 
across  it.  The  grid  coil  is  marked  "L"  and  the  variable  con- 
denser connected  across  it  is  marked  "C."  The  antenna  circuit 
is  not  indicated,  but  let  us  assume  that  oscillations  in  the  an- 
tenna circuit,  in  some  manner,  create  radio-frequency  potential 
variations  at  the  grid  coil  terminals.  If  the  circuit  "LC"  is 
tuned  to  resonance  with  the  antenna  oscillations,  there  will  be 
oscillating  current  of  the  same  frequency   (radio- frequency) 


86  A  B  C  OF  VACUUM  TUBES 

in  this  "closed"  oscillatory  circuit.  The  oscillations  in  this 
circuit  cause  radio- frequency  variations  of  potential  at  the  ter- 
minals of  the  condenser  "C,"  which  are  applied  to  the  grid  of 
the  tube.  Corresponding  variations  of  plate  current  are  there- 
fore produced,  which  flow  through  the  "by-passing  condenser" 
(connected  across  the  telephone  receiver  and  the  plate  battery) 
and  also  through  the  plate  coil.  Being  of  radio- frequency,  these 
plate  current  variations  cannot,  naturally,  flow  very  readily 
through  the  telephone  receiver.  The  radio- frequency  variations 
of  plate  current  are,  of  course,  in  step  with  the  oscillations  in 
the  circuit  "LC"  and,  therefore,  the  oscillating  E.M.F.  induced 
in  that  circuit  by  the  plate  coil  is  also  in  step,  providing  the 
coils  are  connected  in  the  proper  manner.  Some  of  the  energy 
of  the  plate  circuit  oscillations  is  transferred  or  "fed  back"  to 
the  circuit  "LC."  These  oscillations  in  "LC"  are  then  reinforced 
and  the  potential  variations  across  the  condenser  "C"  are  also 
reinforced.  This  in  turn  reinforces  the  potential  variations  on 
the  grid  and  therefore  the  plate  circuit  oscillations.  In  this 
manner  grid  potential  variations  of  radio  frequency  are  in- 
creased sufficiently  in  amplitude  until,  even  with  a  very  weak 
signal,  the  detector  tube  will  be  operated  to  good  advantage. 
The  rectifying  or  detecting  action  of  the  tube  goes  on  at  the 
same  time  so  that  if  the  radio-frequency  antenna  oscillations 
are  in  audio- frequency  groups,  the  telephone  will  respond  to 
the  audio- frequency  variations  of  plate  current  and  the  signal 
is  greatly  amplified  as  well  as  rectified.  In  accordance  with  the 
characteristic  action  of  the  grid  condenser,  this  condenser  is 
charged  in  the  usual  manner,  but  its  charge  at  the  end  of  a 
group  of  oscillations  is  proportional  to  the  resultant  reinforced 
amplitude  of  grid  potential  variations  rather  than  to  the  ampli- 
tude of  radio- frequency  oscillations. 

This  reinforcement  of   grid  potential  variations   is   called 


VACUUM  TUBE  AMPLIFIER  87 

"regeneration,"  and  the  amplification  produced  is  "regenerative 
amplification."  The  idea  is  due  to  E.  H.  Armstrong,  and  this 
circuit  and  its  many  modifications  are  called  "Armstrong 
circuits." 

Autodyne  Production  of  Beats 

If  the  distance  between  the  plate  coil  and  the  coil  "L"  is  de- 
creased it  is  said  that  the  "coupling"  between  them  is  increased. 
If  this  coupling  is  sufficiently  increased  a  click  will  be  heard  in 
the  telephone  receiver.  At  this  instant  radio-frequency  oscilla- 
tions begin  to  be  self -generated  in  the  circuit  "LC,"  whose 
frequency  will  depend  upon  the  inductance  of  the  coil  "L"  and 
the  capacitance  of  the  condenser  "C."  An  increase  in  either 
inductance  or  capacitance  (or  both)  in  this  circuit  will  decrease 
the  frequency  of  the  oscillations.  On  the  other  hand,  a  decrease 
in  either  or  both  will  increase  the  frequency  of  the  oscillations. 

Suppose  that  the  frequency  of  the  antenna  oscillations  is 
100,000  cycles  and  that  of  the  self -generated  oscillations  is 
101,000  cycles.  Currents  of  both  frequencies  flow  in  the  cir- 
cuit "LC,"  although  the  amplitude  of  the  100,000  cycle  oscilla- 
tions will  not  be  as  great  as  though  this  circuit  were  in  resonance 
with  the  antenna  circuit.  Both  oscillations,  antenna  and  sel re- 
generated, are  undamped  (unmodified).  A  third  oscillating 
current  is  produced  in  the  circuit  "LC"  whose  frequency  is 
1000  cycles,  the  numerical  difference  between  the  other  two. 
This  is  the  previously  discussed  heterodyne  action  except  that, 
in  this  case,  the  local  oscillations  are  generated  by  the  detector 
tube  itself.  The  beat  frequency,  in  the  usual  manner,  produces 
1000  variations  of  plate  current  through  the  telephone  receiver 
each  second  and,  this  being  an  audio- frequency,  an  audible  re- 
sponse is  heard  in  the  receiver.  6y  varying  the  frequency  of 
the  locally  generated  oscillations,  the  beat  frequency  and,  there- 


88  A  B  C  OF  VACUUM  TUBES 

fore,  the  tone  of  sound  in  the  receiver  can  be  varied  at  will. 
Undamped  ether  waves  thus  produce  undamped  antenna  oscil- 
lations, which  are  modified  and  rectified  by  the  detector  to  pro- 
duce audible  signals. 

This  method  of  receiving  undamped  wave  signals  is  called 
the  "autodyne"  method  to  distinguish  it  from  the  method  in 
which  local  oscillations  are  generated  by  an  entirely  separate 
device.  It  is,  of  course,  a  "self -heterodyne"  method,  whereas 
that  previously  considered  was  a  "separate-heterodyne"  method. 

If  the  signals  are  damped  waves  or  undamped  waves  modu- 
lated at  any  audible  frequency,  the  tone  produced  in  the  tele- 
phone receiver  will  be  greatly  distorted  due  to  the  interaction 
of  the  various  frequencies,  both  radio  and  audio.  In  the  case 
of  speech  or  music  reception  the  result  is  hopelessly  unsatis- 
factory unless  the  frequency  of  the  local  oscillations  is  exactly 
the  same  as  the  antenna  oscillations.  In  this  case  the  speech  or 
music  will  come  through  without  much  distortion,  usually,  and 
the  amplification  will  be  greatly  increased.  This  is  called  "zero- 
beat"  reception.  No  beat  frequency  is  produced.  When  the 
signals  are  from  a  spark  telegraph  transmitter  or  modulated 
continuous  wave  telegraph  transmitter,  the  natural  group  fre- 
quency of  the  oscillations  will  be  reproduced  and  greatly  ampli- 
fied by  the  zero-beat  method. 

It  is  to  be  noted  that  the  circuit  may  be  exactly  the  same  as 
that  used  for  regeneration.  In  fact,  autodyne  reception  is 
simply  regeneration  carried  to  the  point  where  the  grid  poten- 
tial variations  are  maintained  at  constant  amplitude  whether 
signals  are  being  received  or  not. 

If  the  coupling  between  the  plate  and  grid  coils  is  decreased 
to  a  certain  point,  the  local  oscillations  will  no  longer  be  gen- 
erated. Undamped  (or  continuous)  wave  signals  will  then  no 
longer  be  heard,  although  radio-telephone  signals,  spark  sig- 


VACUUM  TUBE  AMPLIFIER  89 

nals  and  modulated  continuous  wave  telegraph  signals  may  still 
be  heard. 

It  is  interesting  to  note  that  in  the  case  of  "beat  reception" 
of  continuous  wave  signals,  there  are  two  values  of  frequency 
of  local  oscillations  which  may  be  used  to  produce  a  beat  fre- 
quency of,  say,  1000  cycles.  The  numerical  difference  between 
100,000  cycles,  the  frequency  of  the  signal  oscillations,  and 
9900  cycles,  the  frequency  of  local  oscillations,  is  also  1000 
cycles  and  an  audible  beat  frequency.  The  local  circuit  "LC"  of 
Fig.  32  might  be  adjusted  so  that  either  local  frequency  is  pro- 
duced and  with  a  signal  frequency  of  100,000  cycles  (wave 
length  of  3000  meters)  the  audible  beat  frequency  and,  there- 
fore, the  musical  tone  in  the  telephone  receiver  is  the  same, 
1000  cycles. 

There  are  various  modifications  of  the  regenerative  and  self- 
heterodyne  circuit  shown  in  Fig.  33,  but  these  will  be  considered 
in  detail  under  "Practical  Circuits  and  Their  Operation." 


CHAPTER  V 


PRACTICAL  CIRCUITS  AND  THEIR  OPERATION 

Methods  of  coupling — The  variometer — Inter  electrode  tube  capaci- 
tance— Wave  length,  Frequency  and  Resonance — Circuits  and  Explanations 
of  their  arrangement  and  operation. 

Methods  of  Coupling 

Two  circuits,  each  containing  inductance  and  capacitance, 
may  be  coupled  together  in  any  one  of  the  ways  shown  in 
Fig.  34.  If  oscillations  are  present  in  one  of  the  circuits,  oscil- 
lations of  the  same  frequency  will  be  forced  to  flow  in  the  other 
which  is  coupled  to  it.   The  first  circuit  is  called  the  "primary" 


(a)  (b; 

Conductive  Inductive 

Fig.  34 — Methods    of    coupling. 


CO 

Capacftive 


and  the  second  is  called  the  "secondary"  circuit.  The  oscilla- 
tions which  are  forced  to  flow  in  a  secondary  circuit  are  called 
"forced  oscillations."  Their  amplitudes  will  not  be  maximum 
unless  the  secondary  circuit  is  tuned  to  resonance  with  the 
primary.  This  is  true  no  matter  what  kind  of  coupling  is 
considered. 

In   Fig.    34    (a)    the   primary   and   secondary   circuits   are 
coupled   through   the   inductance   which   is   common   to   both 

GO 


CIRCUITS  AND  THEIR  OPERATION  91 

circuits  and  the  coupling  is  called  "conductive."  In  Fig.  34  (b) 
there  is  what  is  known  as  "mutual  inductance"  between  the 
two  coupling  coils.  In  few  words,  there  is  an  inductive 
(inducing)  effect  of  each  coil  upon  the  other,  although  the 
coils  are  not  necessarily  physically  or  electrically  connected 
with  each  other.  This  is  called  "inductive"  coupling.  Fig. 
34  (c)  shows  a  capacitance  to  be  common  to  both  primary  and 
secondary  circuits.  The  coupling  between  the  two  is  made 
through  this  capacitance  and  is,  therefore,  called  "capacitive" 
coupling. 

The  primary  circuit  may  in  any  of  the  above  cases  be 
considered  to  be  an  antenna  circuit,  since  it  contains  both  induc- 
tance and  capacitance. 

The  Variometer 

A  continuously  variable  inductance  is  quite  often  required 
for  the  close  adjustments  frequently  necessary  in  vacuum  tube 
circuits.  If  a  coil  of  wire  is  tapped  at  every  turn  so  that  the 
inductance  may  be  varied  turn  by  turn  the  variation  might 
not  be  smooth  enough.  That  is,  it  might  be  necessary  to 
secure  a  variation  of  inductance  less  than  that  of  one  turn 
on  the  coil.  In  this  case  a  variometer  may  be  used  whose 
construction  may  be  quite  similar  to  that  shown  in  Fig.  35. 
The  coil  which  may  be  turned  is  called  the  "rotor"  and  the 
stationary  coil  is  called  the  "stator."  The  inductance  of  a 
variometer  may  be  varied  by  varying  the  coupling  between 
the  rotor  and  the  stator  which  are  connected  together. 

Inter-Electrode  Tube  Capacitance 

The  filament,  grid  and  plate  of  a  vacuum  tube  all  have  some 
surface  area  and,   in  operation,  have  electric  charges  placed 


92 


A  B  C  OF  VACUUM  TUBES 


upon  them.  It  is  not  hard  to  imagine  them  as  being  plates  of 
small  condensers  with  the  vacuum  space  between  them  acting 
as  a  dielectric.  There  is  thus  capacitance  between  the  tube 
electrodes  which  may  have  certain  effects  upon  the  circuits 
of  the  grid  and  plate.     There  is  a  condenser  effect  between 

.-/Terminals 


Rotor 

Windings^' 


Stator 
Windings  A-'- 


Knob 


^Wire  Connecting 

Stator  to  Rotor 
Fig-  35 — Construction   of    a   typical   variometer. 

the  grid  and  the  plate  and  another  between  the  grid  and  the 
filament.  In  some  cases  the  condenser  effect  may  be  con- 
sidered, as  shown  in  Fig.  36,  where  a  certain  amount  of  capaci- 
tance is  common  to  both  the  grid  and  plate  circuits.  The 
circuits  are  then  considered  as  being  coupled  together  by 
"capacitive"  coupling. 


Wave  Length,  Frequency  and  Resonance 

It  will  be  recalled  that  as  the  frequency  of  ether  oscillations 
decreases,  the  wave  length  of  the  oscillations  increases  and 
vice  versa.  When  a  circuit  is  in  resonance  with  another  at  a 
certain  frequency  it  may  also  be  said  that  they  are  in  resonance 
at  a   certain   wave   length   corresponding   to   that   particular 


CIRCUITS  AND  THEIR  OPERATION 


93 


frequency.  If  the  frequency  is  1,000,000  cycles  per  second, 
the  wave  length  is  300  meters  (300,000,000  meters  per  second, 
being  the  velocity).  The  relation  of  frequency  to  wave  length 
is  thus  clearly  shown.  From  now  on  we  shall  also  think  in 
terms  of  wave  length. 

Now,  it  may  be  recalled  that  the  frequency,  and  we  may 
say  also  the  wave  length,  at  which  any  given  circuit  is  in 

^.Capacitance  Common  to  both 
•  Grid  and  Plate  Circuits 


A 


Grid 

Circuit 


Grid* 


Plate 


Plate  Circuit 


Fig.  36 — Inter-electrode   tube   capacitance, 
resonance   with   another   depends   upon   the   capacitance   and 

inductance  of  the  circuit.  Either  a  comparatively  large  in- 
ductance and  a  small  capacitance  or  a  small  inductance  and 
a  large  capacitance  may  be  used  and,  providing  the  values  of 
each  are  correct  in  each  case,  the  circuit  will  be  in  reso- 
nance. There  may  be  a  preponderance  of  inductance  or  a 
preponderance  of  capacitance.  It  is  neutralization  of  the 
two  opposite  reactances  which  places  a  circuit  in  resonance 
with  another  at  a  particular  frequency  or  wave  length.  Let 
us  consider  a  case  in  point.  Suppose  that  with  an  inductance 
of  10  units  value  and  a  capacitance  of  5  units  value  the  circuit 
is  in  resonance  at  the  wave  length  of  300  meters.  The  circuit 
will  also  be  in  resonance  if  the  inductance  is  of  5  units  and 
the  capacitance  of  10  units  value.  The  product  of  the  two  is 
50  in  each  case.  Now,  the  product  of  a  number  of  other  values 
of  inductance  and  capacitance  may  also  be  50;  for  example, 


94 


A  B  C  OF  VACUUM  TUBES 


inductance  equals  50  units  and  capacitance  equals  1  unit.  So 
long  as  the  product  of  the  two  equals  50,  the  circuit  will,  in 
this  case,  be  resonant  at  the  wave  length  of  300  meters.  This 
is  quite  important  and  must  be  borne  in  mind  in  the  considera- 
tion of  circuit  operation. 


Circuits 

The  circuits  schematically  shown  in  the  following  diagrams 
are  those  which  are  probably  in  most  common  use  and  are 
entirely  practicable.     Many  variations  could  be  made  in  them 


Antenna 


Coupling 
Vario- 
meter 


=5=  Variable 
/-        Condenser 


Grid  Leak 
Resistance 


.Grid 


Grid         \ 
Condenser' 


Telephone 
Receivers 


35p  Ground 

Fig.  37 — Simple    Single    Circuit    Receiver. 


and  there  are  receiving  circuits  almost  by  the  hundreds  which 
are  workable  but  not  in  common  use.  No  attempt  will  be 
made  to  illustrate  every  possible  connection  of  vacuum  tubes 
into  detector  or  amplifier  circuits. 

Fig.  37  is  a  detector  circuit  with  grid  condenser  in  which 
the  coupling  between  the  antenna  and  grid  circuit  is  con- 
ductive.     The    secondary   circuit   is    not   tuned   to    resonance 


CIRCUITS  AND  THEIR  OPERATION  95 

with  the  primary,  although  it  contains  both  inductance  and 
capacitance.  It  may  be  called  an  ' 'untuned  secondary"  circuit. 
A  receiver  with  such  a  circuit  is  said  to  be  a  "single  circuit 
receiver"  because  only  one  circuit,  the  antenna,  is  tunable. 

In  the  operation  of  this  circuit,  the  antenna  is  tuned  to 
resonance  with  the  radio  frequency  oscillations  induced  in  it 
by  the  transmitting  station  it  is  desired  to  receive  from.  If 
the  plate  battery  voltage  and  filament  current  have  been  so 
adjusted  that  the  normal  operating  point  is  on  the  straight 
portion  of  the  characteristic  curve,  signals  of  maximum 
obtainable  audibility  will  be  heard  in  the  pair  of  telephone 
receivers. 

The  circuit  shows  the  antenna  inductance  to  be  a  variometer 
and  it  will  be  good  for  the  reception  of  short  waves.  To 
receive  long  waves  an  inductance,  called  a  "loading  inductance," 
may  be  inserted  in  series  at  point  "X." 

With  this  circuit,  the  ability  to  cut  out  forced  antenna 
oscillations  from  a  station  transmitting  on  a  different  wave 
length  will  depend  upon  the  ratio  of  the  total  antenna  induc- 
tance to  total  antenna  capacity.  By  increasing  the  inductance 
and  simultaneously  decreasing  the  capacitance  a  value  of 
each  will  be  found  which  will  again  put  the  circuit  in  reso- 
nance with  somewhat  greater  freedom  from  interference 
caused  by  the  unwanted  station.  This  is  sometimes  called 
"stiffening"  the  circuit.  There  is  a  drawback  to  this  circuit, 
as  if  the  inductance  of  the  variometer  is  increased,  the  coupling 
between  the  antenna  and  the  grid  circuit  is  also  increased. 
This  would  counteract  the  value  of  stiffening  the  circuit,  since 
increased  coupling  means  increased  liability  of  interference. 
The  disadvantage  could  be  overcome  to  some  extent  by  using 
a  loading  coil.  The  coupling  in  no  case,  however,  may  be 
made  as  loose  as  is   often   desirable   for   the  elimination   of 


96 


A  B  C  OF  VACUUM  TUBES 


strong  interfering  signals  and  atmospherics.  Such  a  circuit 
is  used  for  the  reception  of  damped  waves  only  (spark,  voice, 
etc). 


V- 


Antenna 


Loading 
Variometer 


Coupling 
Variometer 


Grid  Leak 
Resistance 

rp 

UGnW 


*  6 'rid 
Condenser 


42. 

Variable 
Condenser 


Tickler  (Coupling  to 
Variofneteris 
Variable) 


Fig.  38 — Single    Circuit    Regenerative    Receiver. 


Fig.  38  is  practically  the  same  as  Fig.  $j,  with  the  excep- 
tion that  a  plate  coil  is  inductively  coupled  to  the  antenna  vario- 
meter. The  coupling  between  the  variometer  and  plate  coil 
is  variable,  so  that  the  degree  of  grid  potential  reinforcement 
may  be  controlled.  This  plate  coil  is  usually  referred  to  as  a 
"tickler,"  since  it  "tickles"  the  grid  potential  variations,  due 
to  antenna  oscillations.  If  the  coupling  between  the  tickler 
and  the  variometer  is  sufficiently  increased,  oscillations  whose 
frequency  will  be  determined  by  the  antenna  inductance  and 
capacitance  will  be  self-generated  to  produce  beats.  This  is 
the  autodyne  action  previously  discussed.  If  the  coupling  is 
reduced  below  the  point  where  oscillations  are  self -generated, 


CIRCUITS  AND  THEIR  OPERATION  97 

there  is  amplification  by  regeneration  and  this  receiving  circuit 
can  be  made  quite  sensitive  to  weak  signals. 

In  all  other  respects  the  circuit  is  quite  similar  to  that  of 
Fig.  37.  When  the  autodyne  action  is  used  for  the  reception 
of  unmodulated  undamped  waves,  or  "C.  W."  (continuous 
waves),  the  tuning  is  much  sharper  than  when  the  regenerative 
effect  is  used  for  damped  waves.  For  example,  suppose  the  fre- 
quency of  the  desired  signal  to  be  100,000  cycles  (wave  length 
3000  meters)  and  forced  oscillations  in  the  antenna  from  an 
interfering  station  to  be  200,000  cycles  per  second  (wave 
length  1500  meters).  The  frequency  of  local  oscillations  is 
assumed  to  be  101,000  cycles.  The  beat  frequency  produced 
by  the  interaction  of  frequencies  of  100,000  and  101,000  cycles 
is  1000  cycles,  an  audible  frequency.  But  the  beat  frequency, 
due  to  oscillations  of  200,000  and  101,000  cycles,  is  99,000 
cycles,  an  inaudible  frequency.  The  signal  on  the  3000  meter 
wave  would  be  heard  but  that  on  the  1500  meter  wave 
would  not  be  heard  at  all.  Both  might  be  heard  with  a 
single  circuit  receiver,  however,  if  they  were  modified  at  an 
audio- frequency  rate  (or  were  damped  oscillations),  although 
the  receiver  might  be  only  in  resonance  at  the  3000  meter  wave. 

A  receiver  having  such  a  circuit  may  be  called  a  "single 
circuit,  regenerative  receiver." 

The  inductance  and  capacitance  are  sometimes  operated  by 
one  tuning  knob  so  that  both  are  variable  at  the  same  time. 
In  such  a  case  the  single  circuit,  regenerative  tuner  may  be 
made  very  simple  to  operate  and  the  tuning  will  be  fairly 
sharp  so  long  as  the  ratio  of  antenna  inductance  to  capacitance 
is  high  for  all  wave  lengths.  Selectivity,  or  sharpness  of 
tuning,  has  to  be  sacrificed  to  some  extent,  however,  for 
increased. simplicity  of  operation. 

In    Fig.    39    the    antenna    is    inductively    coupled    to    the 


98 


A  B  C  OF  VACUUM  TUBES 


grid  circuit  of  the  detector  tube  and  a  condenser  is  connected 
across  the  secondary  coil  and  variometer.  The  coupling  coils 
may  have  fixed  inductance  and  the  variometers  may  be  used 
for  inductance  variations.  When  the  plate  potential  and 
filament  current  of  the  tube  have  been  adjusted  the  antenna 


Antenna 


Fixed 

Primary 

Inductance, 


Loading 
Variometer 


Grid, 
Leak 


Fixed 
'Secondary 
Induct. 


i\\7~\'^r/^  Condenser' 


Variable » 
Secondary 
Capacitance 


Aim 


7 


-=-  Plate 
kfilRheo.     -=- Battery 

_l±  :     ~^~ 


J" 


Fit. 
Battery 


Phones 


—  Ground. 

Fig"-  39 — Two   Circuit   Receiver,   Inductive   Coupling. 


may  be  tuned  to  resonance  with  a  signal  by  varying 
either  the  inductance  of  the  variometer  or  the  capacitance  of 
the  condenser  in  that  circuit.  Large  values  of  inductance  and 
small  values  of  capacitance  should  be  used  for  sharp  tuning. 
Oscillations  are  then  induced  in  the  secondary  circuit  and 
their  amplitudes  made  maximum  by  tuning  the  circuit  to 
resonance  with  the  antenna.  The  secondary  variometer  and 
condenser  are  used  for  this  purpose.  Large  values  of  induc- 
tance and  small  values  of  capacitance  for  resonance  should  also 
be  used  here.    A  decrease  of  coupling  decreases  the  amplitudes 


CIRCUITS  AND  THEIR  OPERATION 


99 


of  the  secondary  oscillations,  but  increases  the  sharpness  of 
tuning.  The  object  is,  then,  to  use  as  little  coupling  as  possible 
without  reducing  the  signal  too  greatly.  When  coupling 
adjustments  are  made  it  will  be  found  necessary  to  slightly 
alter  the  resonance  adjustments  of  both  the  antenna  and 
secondary  circuits.  Variations  of  coupling  have  an  effect 
upon  the  inductance  values. 

With  this  circuit  the  sharpness  of  tuning  may  be  increased 
very  materially  over  that  possible  with  any  single  circuit.  A 
receiver  having  this  sort  of  circuit  might  be  called  a  "two- 


Variable 
Primary 
Inductance 


# 


(Antenna 


loading 
Variometer 


in 


Mar.  Sec. 

\  Induct. 


Tickler 


^-Variable 
Coupling 


£ 


Grid 
Leak 

□3 


■Grid  Condenser 


Variable 


A 


Capacitance 


FiLRheo. 


7"  n  + 


Fit 


±t 


Plate 
Bat- 
tery 


r-Batten/^J  Phones 


By  Pass- 
ing Con- 
denser 


Fig.  40 — Two    Circuit    Regenerative    Receiver,    Inductive    Coupling. 


circuit  receiver,"  because  there  are  two  circuits  to  tune. 

Oscillations  in  the  secondary  circuits,  of  course,  cause  oscil- 
lating potential  variations  to  be  applied  to  the  grid  of  the  tube, 
but  there  is  no  regeneration  and  it  is  possible  for  a  signal  to 
be  too  weak  to  operate  the  detector.    The  circuit  is  not  adapted 


ioo  ABC  OF  VACUUM  TUBES 

to  the  reception  of  unmodified  continuous  waves,  but  may  be 
used  for  damped  waves  (  spark,  radio-telephone,  etc. ) . 

Fig.  40  is  almost  exactly  the  same  circuit  as  in  Fig. 
39,  except  that  regeneration  may  be  had  by  means  of 
the  tickler  coupling.  Here  again  the  unmodified  continuous 
wave  signals  may  be  received  by  the  beat  method  if  local 
oscillations  of  the  proper  frequency  are  generated.  The 
frequency  of  the  local  oscillations  is  controlled  by  the  adjust- 
ment of  secondary  inductance  and  capacitance.  Sharpness 
of  tuning  may  still  be  had  because  of  beat  reception  in  the  same 
manner  as  set  forth  in  the  discussion  of  Fig.  38. 

When  regeneration  is  used  the  signals  may  be  continuously 
amplified  by  increasing  the  tickler  coupling  up  to  the  point 
where  local  oscillations  start.  Just  before  the  oscillations  start 
the  undamped  wave  signals  will  be  loudest,  but  after  that 
degree  of  coupling  is  passed  the  locally  generated  oscillations 
will  distort  the  tone  if  beats  are  produced.  In  the  case  of 
radio-telephone  reception  this  would  make  speech  either  hard  to 
understand  or  even  unintelligible.  Beats  may  be  avoided,  even 
though  local  oscillations  are  generated,  by  tuning  the  secondary 
to  exact  resonance  with  the  antenna  circuit.  Reception  is 
then  accomplished  by  the  zero-beat  method.  This  will  give 
maximum  amplification  of  all  damped  wave  signals,  but  in 
the  case  of  voice  or  music  there  may  be  some  slight  distortion, 
due  to  the  varying  tone  frequency. 

In  the  reception  of  straight  undamped  waves  there  are,  of 
course,  locally  generated  frequencies  both  above  and  below 
the  signal  frequency  which  will  give  beat  reception.  The 
following  is  an  interesting  experiment.  Adjust  the  tickler 
coupling  until  local  oscillations  are  fairly  strong.  Then, 
starting  with  a  secondary  circuit  adjustment  such  that  the 
frequency  of  generated  oscillations  is  somewhat  above  that  of 


CIRCUITS  AND  THEIR  OPERATION 


IOI 


the  signal  oscillations,  increase  the  secondary  capacitance  grad- 
ually. This  decreases  the  frequency  of  the  local  oscillations 
and  the  beat  tone  until  finally  no  sound  is  heard.  Then  keep 
on  increasing  the  capacitance  to  still  further  decrease  the 
frequency  of  the  local  oscillations  below  that  of  the  signal 
oscillations.  This  increases  the  difference  between  the  two 
frequencies  and  the  beat  tone  increases.  When  no  signal  was 
heard  the  beat   frequency  was,  of  course,   zero    (zero-beat). 


1 'Antenna 


P/afe 
Variometer 


=5*    Coupling 
Ground^ 


'Grid 
Variometer 


Phones 
Fig.  41 — Three   Circuit   Regenerative   Receiver   for   Short  Waves. 


In  Fig.  41  the  antenna,  grid  and  the  plate  circuit  may 
be  tuned — three  circuits.  The  third,  or  plate,  circuit  may 
be  called  the  "tertiary"  circuit.  Both  the  grid  and  plate  circuits 
contain  a  certain  amount  of  capacitance,  due  to  the  capacitance 
within  the  tube.  The  tube  capacitance  in  this  kind  of  circuit 
is  the  main  means  of  feeding  back  energy  from  the  plate  to 
the  grid  circuit.  Either  circuit  may  be  tuned  by  varying  the 
inductance  of  a  variometer.  There  are  two  variometers,  the 
"grid  variometer"  and  the  "plate  variometer,"  shown  in  the 
figure. 

The  circuit  illustrated  is  better   for  the  very  short  waves 


102  ABC  OF  VACUUM  TUBES 

than  it  is  for  the  longer  because  of  the  small  inter-electrode 
capacitance  of  the  tube. 

In  the  reception  of  damped  wave  signals  (spark,  voice,  etc.) 
the  antenna  is  tuned  to  the  signal  wave  and  the  grid  circuit 
tuned  to  the  antenna  in  the  usual  manner.  As  the  plate  vario- 
meter inductance  is  increased  from  a  minimum  value  the 
oscillating  grid  potentials  become  more  and  more  greatly  rein- 
forced until  a  certain  inductance  value  is  reached  which  puts 
the  plate  circuit  in  resonance  with  the  grid  circut.  The  recti- 
fying action  goes  on  at  the  same  time  as  does  the  amplification 
due  to  regeneration.  The  result  in  the  telephone  receivers 
is  then  maximum  when  all  three  circuits  are  in  resonance. 

An  autodyne  action  may  also  be  secured  for  the  production 
of  a  beat  frequency  when  the  reception  of  continuous  waves 
is  desired.  Local  oscillations  may  be  generated  in  the  tube 
circuits,  providing  the  capacitive  coupling  between  plate  and 
grid  circuits  is  large  enough.  The  frequency  of  the  self- 
generated  oscillations,  in  the  circuit  under  consideration,  will 
not  depend  very  closely  upon  the  inductance  and  capacitance 
of  the  grid  circuit  because  the  plate  circuit  will  exert  a  some- 
what greater  influence.  By  adjusting  both  the  grid  and  plate 
variometers,  however,  a  local  oscillation  frequency  will  be 
secured  which  will  produce  the  desired  beat  tone  in  the  tele- 
phone receivers.  One  circuit  has  a  tendency  to  pull  the  other 
into  step  with  it  in  a  manner  quite  similar  to  that  of  the 
synchronization  of  two  alternating  current  generators  at  a 
power  station. 

Fig.  42  is  quite  similar  to  that  of  the  preceding  circuit 
with  the  exception  of  a  variable  capacitance  used  to  couple 
the  grid  and  plate  circuits.  This  capacitance  may  be  used  to 
increase  the  tube  capacitance  and  therefore  the  coupling 
between   the   tube   circuits.      By   increasing   this   capacitance 


CIRCUITS  AND  THEIR  OPERATION 


IO~, 


(switch  closed)   the  operation  becomes  more  effective  at  the 
longer  waves  (lower  frequencies). 

In  all  other  respects  this  circuit  is  practically  the  same  in 
operation  as  the  preceding  one. 


Antenna 


w 


Variable 

Tuning 

Induct 


Grid 

Variometer 


Switch 
►o 


Var,  Coupling 
Capacitance 


Plate 
Variometer 


-smfo-1 — I— II— 1 
A~    joj         OridWof 


Variable  Coupling 


Plate 
Battery 


or  Phones 


■Negative  Plate  Battery 
Terminal  Grounded  here 
(Puts  that  Terminal  at 
Ground  Potential  to 
Avoid  Capacity  Effect) 


"W  Ground 
Fig.  42 — Three  Circuit  Regenerative  Receiver  for  Short  and  Medium  Waves. 


In  Fig.  43  is  shown  the  schematic  circuit  of  a  two  stage 
audio- frequency  amplifier  coupled  to  a  detector.  If  in  any  of 
the  previous  circuits  the  grid  circuit  of  the  first  amplifier 
tube  is  connected  into  the  plate  circuit  of  the  detector  tube 
(through  the  transformer)  in  place  of  the  telephone  receivers, 
the  detector  energy  at  audio- frequency  may  be  amplified.  The 
connections  are  only  shown  for  one  type  of  detector  circuit. 
The  operating  point  must  be  adjusted  to  the  straight  portion  of 
the  characteristic  curve  in  the  case  of  each  of  the  amplifier 
tubes  in  order  to  avoid  distortion  effects.  This  is  done  by 
applying  a  normal  negative  potential  to  the  grids  in  the  manner 


104 


A  B  C  OF  VACUUM  TUBES 


shown  and  by  adjusting  the  plate  battery  voltage  and  filament 
current  to  the  proper  values.  It  is  customary  to  burn  the  fila- 
ment at  a  constant  voltage  rather  than  at  a  constant  current, 
since  this  increases  the  life  of  the  filament.     It  may  then  be 

W 

<■  Coupling 

Transformers 


for  one  Stage 


Fig.  43 — Two  Circuit  Receiver  with  Two- Stage  Audio- frequency  Amplifier. 

No  Regeneration. 

necessary  to  vary  the  plate  battery  voltage  from  time  to  time 
as  the  filament  ages. 

The  coupling  transformers  have  closed  iron  cores  like  the 
illustration  of  Fig.  44. 

The  upper  Fig.  45  shows  a  two  stage  resistance  coupled  radio- 
frequency  amplifier  connected  to  a  detector  circuit.  The 
antenna  and  secondary  circuits  are  tuned  to  the  signal  wave 
and  the  oscillating  potentials  applied  to  the  grid  circuit  of 
the  first  amplifier  tube  are  of  radio- frequency.  The  oscillating 
potentials  applied  to  the  grid  circuit  of  the  detector  tube  are 
thereby  amplified  and  result  in  greatly  amplified  plate  current 


CIRCUITS  AND  THEIR  OPERATION 


105 


variations  in  this  detector  circuit.  If  care  is  taken  to  operate 
the  amplifier  tubes  with  the  operating  points  on  the  straight 
portion  of  their  characteristic  curves,  distortion  can  usually 
be  avoided. 

The  resistance  coupled  radio- frequency  amplifiers  are  some- 
what more  suited  to  the  longer  wave  lengths  (lower  radio- 
frequencies)  and  one  of  their  big  disadvantages  is  that  a  high 


Secondary 
Wires 


™  Prima/ y 
Wires 


<  Closed. 
Iron  Core 

(Secondary  Wound 
overPrimary) 


Fig.  44 — Typical    audio-frequency   coupling   transformer. 


plate  battery  voltage  is  necessary  to  pass  sufficiently  large 
plate  currents  through  the  coupling  resistances.  For  this 
reason  it  is  common  practice  to  use  specially  designed  radio- 
frequency  transformers  (lower  figure)  in  place  of  the  resist- 
ances. The  transformers  are  usually  better  at  the  lower 
frequencies  (longer  waves),  but  the  chances  appear  to  be  good 
to  use  them  even  with  the  very  short  waves.  One  big  advan- 
tage they  have  is  that  a  large  plate  battery  voltage  is  not 
required. 

In  the  case  of  transformers,  the  iron  core  must  be  very 
carefully  constructed  so  that  too  much  loss  of  energy  will 
not  take  place  in  the  core  itself.  Usually  it  is  difficult  to 
eliminate  the  core  losses  to  any  very  great  extent  when  opera- 
tion is  with  high  frequency  currents.  The  subject  of  design, 
however,  is  beyond  the  scope  of  this  little  book. 

In  Fig.  46  the  schematic  connections  of  a  three  stage  radio- 


io6 


A  B  C  OF  VACUUM  TUBES 


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Coupling 
Resistances 


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Plate  Battery 
for  Detector 


w 


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Transformer.  zi'Zt* 


Variable 
Coupling 


Plate  Battery 

tH  lining 


Fig.  45 — Two  circuits    for   radio-frequency   amplification  and  detection. 
Two  Circuit  Receivers  in  Each  Circuit. 


CIRCUITS  AND  THEIR  OPERATION 


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frequency  amplifier,  detector  and  three  stage  audio-frequency 
amplifier  are  shown.  If  distortion  is  to  be  avoided  in  such 
a  circuit  (or  circuits)  great  care  must  be  taken  to  have  the 
proper  potentials  applied  to  the  grids  of  the  amplifier  tubes. 
Enormous  amplification  can  be  secured,  however,  and  enough 
current  variation  produced  in  the  plate  circuit  of  the  last 
audio- frequency  stage  to  operate  a  relay  or  a  "loud-speaker" 


Antenna^/     C$f}fn9 

s''    Grid 
Variometer 


Variable 
Antenna 
Induct 


Plate 
Variometer 


Audio  Freq. 

Coupling 

^Transformers 


Variable 
Tuning 
Condenser 


Ground 


Plate  Battery 


Fig.  47 — Suggestion  for  Short  Wave  Regenerative  Receiver  and  Two  Stage 

Audio- frequency  Amplifier. 


on  an  extremely  weak  signal  which  could  not  possibly  be 
heard  with  a  detector  and  audio- frequency  amplifier  alone. 

Distortion  can  be  avoided  even  in  such  a  complicated  ampli- 
fier with  many  stages,  and  distortion  of  speech  will  be  taken 
up  in  the  next  chapter. 

The  circuit  of  Fig.  47  eliminates  the  necessity  of  a  by-pass 
condenser  in  the  plate  circuit.  In  the  usual  circuit  this  by-pass 
condenser  is  required  to  permit  the  plate  circuit  oscillations, 


CIRCUITS  AND  THEIR  OPERATION 


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since,  without  it,  the  inductive  reactance  of  the  telephone 
receivers  would  be  too  great  to  pass  these  oscillations. 

The  circuit  is  very  effective  and  operates  in  a  manner  almost 
identical  with  that  of  previous  tuned  plate  circuits. 

It  may  be  said,  in  this  connection,  that  all  circuits  in  which 
the  plate  is  also  tunable  are  called  "tertiary  tuned  circuits" 
and  that  receivers  so  designed  are  called  "three  circuit 
receivers." 

The  circuit  is  shown  connected  to  a  two  stage  audio- 
frequency amplifier. 


CHAPTER  VI 

Voice  Distortion 

Amplifier    transformers — Normal    grid    potential — Too    great    regen- 
eration— Telephone   receiver. 

If  speech  and  music  are  received  from  a  given  station 
without  distortion  on  a  crystal  detector  and  distortion  is 
encountered  when  the  crystal  is  replaced  by  vacuum  tube 
circuits,  it  may  be  easily  assumed  that  the  distortion  is  caused 
in  the  receiving  circuits.  It  may,  therefore,  be  of  interest  to 
consider  some  of  the  causes  of  voice  distortion  in  a  receiver 
and  amplifier. 

Amplifier  Transformers 

Distortion  is  often  due  to  a  poorly  designed  coupling  trans- 
former in  the  case  of  either  audio  or  radio- frequency  cascade 
amplification.  The  distortion  will  in  this  case  be  produced 
regardless  of  the  degree  of  care  taken  to  prevent  it  in  other 
directions.  The  remedy  is,  of  course,  a  properly  designed 
transformer. 

Grid  Potential 

It  has  already  been  pointed  out  that  in  the  case  of  either 
audio  or  radio- frequency  cascade  amplification  it  is  quite  neces- 
sary to  have  the  operating  point  of  each  amplifier  tube  on  the 
straight  portion  of  the  characteristic  curve.  Moreover,  it  should 
be  as  nearly  as  possible  at  the  middle  of  the  straight  portion,  so 
that  neither  a  large  positive  or  a  large  negative  value  of  applied 

in 


ii2  A  B  C  OF  VACUUM  TUBES 

grid  potential  (due  to  the  signal)  will  swing  the  resultant  grid 
potential  down  to  the  "cut-ofT"  value  or  up  to  the  value  where 
plate  saturation  takes  place.  In  order  to  accomplish  these 
desired  results  in  practice,  it  is  desirable  to  have  a  sufficiently 
large  plate  battery  voltage  (normal  plate  potential)  and  a 
sufficiently  large  normal  negative  potential  on  the  grid.  The 
desired  grid  potential  is  preferably  secured  by  including  a 
sufficient  amount  of  the  filament  rheostat  resistance  in  the  grid 
circuit.  The  manner  of  accomplishing  this  has  been  previously 
pointed  out. 

In  some  cases,  however,  the  input  (applied)  grid  potential 
variations  may  be  too  great  in  amplitude,  even  though  the 
above  precautions  are  taken.  This  is  a  result,  usually,  of  too 
much  regeneration,  even  though  local  oscillations  may  not  be, 
at  the  same  time,  produced.  With  a  regenerative  receiver  it 
quite  frequently  happens  that  operation  will  be  without  distor- 
tion until  a  loud  tone  causes  the  grid  potential  to  shoot  up  and 
a  loud  blaring  noise  to  be  heard.  In  this  case,  sacrifice  some 
audibility  by  reducing  the  tickler  coupling  (or  readjusting 
the  plate  variometer)  and  with  it  the  degree  of  regeneration. 
More  nearly  distortionless  reception  will  result.  This  kind  of 
distortion  (due  to  too  great  input  voltage)  may  also  be  caused 
by  using  too  many  stages  of  amplification  with  too  little  plate 
voltage  in  the  circuits  of  the  last  amplifier  tubes.  Increase  of 
plate  voltage  will  frequently  correct  the  trouble,  but  if  not,  then 
a  small  power  amplifier  tube  may  be  used  and  large  plate  voltage 
applied  to  it.  This  is  one  reason  why  more  than  two  or  three 
stages  of  audio- frequency  cascade  amplification  are  inadvisable. 

If  the  signal  is  very  weak,  serious  distortion  may  be  caused 
by  a  flow  of  grid  current  when  the  resultant  grid  potential 
periodically  reaches  a  positive  value.  This  would  cause  actual 
rectification  in  the  grid  circuit  and,  therefore,   distortion  of 


VOICE  DISTORTION  113 

the   plate   current   variations.      The   remedy   is   to   apply   the 
proper  value  of  normal  negative  grid  potential. 

When  an  amplifier  cabinet  has  been  properly  designed, 
provision  has  been  made  for  the  proper  normal  negative  grid 
potential  when  the  filament  current  is  of  normal  value.  In 
the  operation  of  such  a  cabinet  amplifier  it  is  then  only  neces- 
sary to  secure  the  proper  amount  of  filament  current  (adjus- 
table at  the  rheostat)  and  the  proper  value  of  plate  battery 
voltage. 

Too  Great  Regeneration 

In  any  kind  of  a  regenerative  circuit  receiver,  too  much 
regeneration  will,  as  has  been  pointed  out,  cause  distortion 
of  the  loud  tones.  To  avoid  this  distortion  care  must  be  taken 
that  the  operation  is  below  the  point  where  oscillations  start. 
Regeneration  in  any  degree  also  has  a  tendency  to  either  subdue 
or  slightly  distort  the  delicate  overtones  and  harmonics  of 
sound.  Better  reproduction  of  voice  and  music  is  secured  when 
no  regeneration  is  used,  but  the  tendency  is  to  use  it  to  increase 
the  volume  of  sound.  A  better  way  would  be  to  use  a  tuned 
secondary  circuit  with  a  straight  detector  (no  feed-back)  and 
to  bring  up  the  volume  by  cascade  audio- frequency  ampli- 
fication in  as  few  stages  as  possible.  The  number  of  stages 
necessary  is  reduced  when  power  (or  transmitting)  tubes  are 
used  with  large  plate  voltages. 

Overloading  of  Tubes 

It  was  stated  above  that  by  increasing  plate  battery  voltage 
certain  causes  of  distortion  might  be  overcome.  If  the  voltage 
is  higher,  however,  than  that  at  which  the  tube  is  rated, 
distortion  may  be  caused  by  overloading.     The  rule  then  would 


H4  A  B  C  OF  VACUUM  TUBES 

be  to  use  the  power  tubes,  which  will  permit  of  the  large 
plate  voltages  without  overloading.  It  is  understood  that 
the  use  of  power  tubes  for  amplification  means  extra  expense 
for  both  the  tubes  and  the  plate  batteries,  but  the  result  is 
usually  worth  the  investment. 

Telephone   Receiver 

Some  telephone  receivers  are  inherently  prone  to  cause  dis- 
tortion, but  this  is  a  matter  of  selection  of  equipment.  Also, 
if  the  audio- frequency  plate  current  variations  are  of  too 
great  amplitudes  the  receiver  diaphragms  may  rattle.  The 
rattling  is  often  directly  due  to  such  strong  vibrations  that 
the  diaphragm  hits  the  magnet  poles.  Sometimes,  but  not 
always,  this  rattling  may  be  stopped  by  screwing  the  receiver 
cap  on  tighter  to  prevent  the  diaphragm  from  "jumping." 
Another  cause  of  distortion  in  a  telephone  receiver  is  the 
resonance  had  at  times  between  the  natural  period  of  vibration 
of  the  diaphragm  and  the  tone  frequency.  This  is  again,  how- 
ever, a  matter  of  selecting  a  pair  of  receivers  to  avoid  the 
effect.  Some  "loud  speakers"  are  made  of  a  telephone  receiver 
connected  with  a  horn.  In  such  cases  resonance  effects  may 
be  had  in  the  diaphragm  or  in  the  horn  itself  if  it  is  of  metal. 
The  design  of  an  ideal  loud  speaker  is  still  a  goal  to  be  attained, 
although  some  types  approach  the  ideal  quite  closely. 

Conclusion 

Absolute  absence  of  all  distortion  is  almost  impossible,  since 
mechanical  and  electrical  devices  cannot  be  made  absolutely 
perfect  reproducers  of  the  human  voice.  Perfection  may  be, 
and  is,  however,  closely  approximated  when  care  is  taken  in 


VOICE  DISTORTION  115 

the  design  and  operation  of  apparatus.  This  must  not  be 
taken  to  mean  that  very  fine  practical  results  in  voice  repro- 
duction are  only  accomplished  with  great  difficulty.  Very 
fine  results  may  indeed  be  obtained  with  present  equipment 
if  the  comparatively  few  precautions  are  observed  in  operation. 
There  probably  will  always  be  room  for  some  improvement, 
however,  as  is  the  case  with  most  things. 


CHAPTER    VII 
PRACTICAL  QUESTIONS  AND  ANSWERS 

1.  Can  insulated  wires  be  used  in  an  antenna  (or  aerial)  ? 
Arts.    Yes,  since  the  ether  waves  pass  through  insulating 

materials  very  readily. 

2.  How  many  wires  are  necessary  in  a  receiving  antenna  ? 
Ans.    Only  one  wire  is  necessary  and  there  is  no  practical 

advantage  in  using  more  than  one. 

3.  What  kind  of  wire  should  be  used? 

Ans.  Any  kind  of  copper,  aluminum,  phosphor  bronze  or 
silicon  bronze  wire  may  be  used.  Even  iron  wire  may  be  used 
in  some  cases,  although  it  is  not  recommended.  The  wire 
used  should  have  sufficient  tensile  strength  to  stand  the  strains 
imposed  upon  it  by  the  weight  of  a  span  and  the  wind  pressure 
against  it.  It  should  be  of  low  resistance  to  high  frequency 
alternating  current.  Since  the  radio- frequency  oscillations  in 
an  antenna  travel  mostly  upon  the  surface  of  the  conductor,  a 
copper  clad  wire  may  be  used.  A  stranded  phosphor  bronze  or 
silicon  bronze  wire  has  good  tensile  strength  and  is  a  very 
good  conductor  of  high  frequency  current. 

4.  Is  it  absolutely  necessary  to  insulate  an  antenna  ? 

Ans.  In  dry  weather  an  uninsulated  antenna  may  be  used 
without  much  leakage.  In  damp  weather,  however,  it  is 
quite  necessary  to  have  the  antenna  insulated  at  all  points  of 
support.    Ordinary  porcelain  insulators  are  suitable. 

5.  Is  it  necessary  to  have  the  antenna  as  far  as  possible 

from  metallic  objects  and  structures? 

116 


QUESTIONS  AND  ANSWERS  117 

Ans.  It  is  always  best  to  keep  the  antenna  as  far  away  from 
metallic  structures  as  possible.  It  is  not  absolutely  necessary 
to  have  it  any  great  distance  away,  but,  in  general,  the  further 
away  the  better  the  results. 

6.  Is  it  necessary  to  solder  the  joints  in  a  receiving 
antenna  ? 

Ans.  It  is  highly  advisable  to  do  so,  particularly  if  the 
antenna  is  to  be  more  or  less  permanent.  The  corrosion  of 
the  wire  at  the  joints  will  increase  the  resistance  at  those  points 
unless  the  joints  are  soldered.  A  non-corrosive  flux  should 
be  used  in  soldering.  At  best,  the  oscillating  current  flowing 
in  a  receiving  antenna  circuit  is  of  small  value,  and  it  is  very 
necessary  not  to  allow  the  antenna  resistance  to  be  any  greater 
than  can  be  helped.  The  lower  the  resistance  the  stronger  the 
current  which  will  flow  in  the  antenna,  all  other  things  being 
equal. 

7.  Where  should  the  lead-in  from  the  antenna  be  connected 
to  it? 

Ans.  It  should  be  connected  to  that  end  of  the  antenna 
which  is  nearest  the  station  it  is  particularly  desired  to  receive 
from.  If  this  cannot  be  done  the  lead-in  may  be  connected  to 
the  middle  of  the  antenna,  providing  the  horizontal  part  is 
long  enough.  In  the  former  case  there  would  be  an  inverted 
"L"  and  in  the  latter  a  "T"  type  antenna  thereby  secured. 
The  wave  length  is  somewhat  decreased  when  the  lead  is  taken 
from  the  middle  of  any  given  horizontal  portion.  If  it  is 
not  practicable  to  erect  an  antenna  with  a  horizontal  portion, 
a  nearly  perpendicular  wire  may  be  suspended  from  a  high 
object. 

8.  How  long  should  the  antenna  be? 

Ans.  This  depends  upon  the  wave  lengths  to  be  received. 
The  horizontal  portion  may  be  about  100  feet  long  for 
the  short  waves,   200   feet  long   for  moderate  length  waves 


n8  A  B  C  OF  VACUUM  TUBES 

and  300  feet  for  the  long  waves.  The  antenna  should  not  be 
over  about  fifty  or  sixty  feet  high  from  the  ground  or  from 
the  top  of  a  building  with  the  above  lengths.  If  the  height  is 
reduced  the  wire  may  be  made  somewhat  longer.  A  total 
length  of  wire  (horizontal  part  plus  lead-in)  may  well  be 
about  150  or  160  feet  for  short  wave  reception. 

9.  How  high  should  the  antenna  be? 

Ans.  This  is  partially  answered  in  the  above.  In  general, 
the  higher  the  better.  The  height  of  an  antenna  erected  upon 
a  roof  should  be  reckoned  from  the  roof  upwards,  unless  only 
a  comparatively  small  portion  of  the  antenna  is  directly  above 
the  roof.  If  the  antenna  is  in  an  open  space  with  no  buildings 
or  only  small  sheds  beneath  it,  the  height  may  be  reckoned  from 
the  ground,  providing  the  receiving  apparatus  is  at  or  near  the 
ground  level. 

10.  Can  a  gas  pipe,  fire  escape,  drain  pipe,  and  so  forth,  be 
used  for  an  antenna? 

Ans.  In  some  cases  any  one  of  them  might  be  used,  pro- 
viding efficient  receiving  apparatus  is  used  at  the  same  time. 
A  gas  pipe  has  been  known  to  equal  a  rather  poor  antenna  for 
receiving,  but  vacuum  tubes  and  not  a  crystal  detector  were 
used.  Bed  springs  may  be  sometimes  used  for  antenna,  pro- 
viding the  transmitting  station  is  not  too  far  away.  The 
regular  antenna  gives  better  results  usually  in  all  cases. 

1 1 .  How  shall  the  ground  be  arranged  ? 

Ans.  A  counterpoise  ground  composed  of  wires  insulated 
from  the  earth  and  radiating  from  the  receiving  station  at  a 
height  of  about  ten  feet  from  the  earth  makes  a  very  fine 
ground  because  of  its  comparatively  low  resistance.  This  is 
not  possible  in  many  cases,  and  even  when  possible  the  results 
sometimes  do  not  justify  the  trouble  and  expense.  This  kind 
of  a  "ground"  is  highly  desirable  for  transmitting,  however. 


QUESTIONS  AND  ANSWERS  119 

The  next  best  arrangement  is  connection  to  the  cold  water 
pipe.  The  connection  should  be  well  made.  If  this  is  not 
possible  the  ground  wire  may  be  connected  to  a  radiator  pipe 
and  very  good  results  are  often  had. 

12.  May  a  loop  antenna  be  used  to  good  advantage? 
Ans.    A  loop  may  be  used  to  very  good  advantage,  providing 

it  is  of  the  proper  dimensions  for  the  wave  lengths  to  be 
received,  and  providing  the  proper  receiving  equipment  is  used 
with  it.  Usually  it  is  necessary  to  use  radio- frequency  cascade 
amplification  if  the  transmitting  station  is  some  distance  away. 
The  loop  antenna  may  be  used  to  eliminate  much  of  the  inter- 
ference encountered  with  a  regular  antenna  and  the  loop  should 
be  arranged  to  rotate  so  that  its  position  may  be  set  for  recep- 
tion from  a  particular  station.    The  loop  is  very  directional. 

13.  May  a  loading  coil  be  used  to  increase  the  wave  length 
of  the  antenna? 

Ans.  Yes,  a  loading  coil  may  be  used,  and  if  the  amount 
of  inductance  required  is  not  too  great  a  variometer  makes  a 
very  fine  loading  coil.  If  the  antenna  is  "loaded"  it  is  usually 
also  necessary  to  load  the  secondary  circuit  of  the  tuner,  if.it 
is  of  the  two  circuit  type.  If  there  is  a  tertiary  circuit  (tuned- 
plate  circuit)  it  is  sometimes  necessary  to  load  that  circuit  also. 

14.  Why  is  a  variometer  better  for  a  loading  inductance 
than  a  tapped  coil  or  one  with  a  slider  ? 

Ans.  Because  finer  variations  of  inductance  may  be  secured 
with  the  variometer. 

15.  What  is  the  advantage  of  using  a  condenser  in  series 
with  the  antenna  ? 

Ans.  If  the  condenser  is  variable  the  wave  length  of  the 
antenna  may  be  made  closely  variable  within  certain  limits. 
Another  advantage  is  that  the  ratio  of  inductance  to  capacitance 
may  be  increased  when  tuning  to  a  given  wave  length.     An 


120  A  B  C  OF  VACUUM  TUBES 

increase  in  this  ratio  means  increased  selectivity  or  less  liability 
to  interference  from  stations  transmitting  on  different  wave 
lengths.  Close  tuning  is  very  desirable,  but  the  necessary 
adjustments  are,  of  course,  increased. 

1 6.  Is  a  vario-coupler  better  than  a  loose-coupler  for  use  in 
a  receiving    circuit? 

Ans.  A  vario-coupler  usually  gives  the  better  results  because 
it  generally  allows  a  variation  of  coupling  without  much  sepa- 
ration of  the  two  coils. 

17.  Is  it  advisable  to  use  low  values  of  capacitance  (capac- 
ity) in  the  secondary  condenser  for  tuning  to  a  given  wave 
length? 

Ans.  Yes,  a  predominance  of  inductance  in  this  circuit  for 
any  given  wave  length  is  advisable  when  a  vacuum  tube  detector 
is  used.  In  any  case,  the  increase  in  ratio  of  inductance  to 
capacitance  makes  for  sharper  or  closer  tuning.  In  the  case 
of  very  short  waves  it  is  often  advisable  to  eliminate  the 
secondary  condenser  entirely  and  use  a  variometer  for  tuning 
the  grid  circuit  of  a  vacuum  tube  detector.  In  the  case  of 
crystal  detector  reception  the  elimination  of  the  secondary 
condenser  will  often  increase  the  signal  strength  but  decrease  to 
some  extent  the  sharpness  of  tuning. 

18.  Will  the  use  of  a  loading  coil  decrease  the  range  of 
reception  ? 

Ans.  Not  so  long  as  the  resistance  of  the  winding  is  not 
too  high.  In  practice  it  will  not  reduce  the  range,  nor  will  it 
increase  it. 

19.  Is  it  advisable  to  burn  a  vacuum  tube  filament  very 
brightly  ? 

Ans.  No,  it  is  not  advisable  to  burn  it  any  more  brightly 
than  is  absolutely  necessary.  Burning  it  less  brightly  increases 
its  life  and  very  often  a  weaker  signal  in  the  head-phones  is 


QUESTIONS  AND  ANSWERS  121 

more  advisable  than  a  very  brilliantly  glowing  filament.  It 
has  been  found  that  if  a  filament  is  operated  with  a  constant 
voltage  between  its  terminals  its  life  is  very  greatly  in- 
creased. 

20.  May  alternating  current  be  used  to  light  a  filament? 
Ans.    It  is  not  advisable  in  the  case  of  a  receiver  because 

there  is  usually  an  annoying  hum  even  when  precautions  are 
taken  to  eliminate  it.  Furthermore,  a  step  down  transformer 
is  necessary,  as  a  tube  filament  would  be  promptly  burned  out 
if  connected  to  a  no  volt  alternating  current  circuit.  The 
voltage  from  the  transformer  secondary  should  be  six  volts 
and  a  potentiometer  may  be  connected  directly  across  the  fila- 
ment leads  with  the  potentiometer  slider  connected  to  the  grid 
circuit.  The  grid  circuit  is  not  then  connected  to  one  side  of 
the  filament,  but  rather  to  a  point  on  the  potentiometer  resist- 
ance which  gives  a  zero  potential  of  grid  with  respect  to  fila- 
ment at  any  instant.  This  theoretical  result  is  difficult  to 
attain  in  practice  and  there  are  many  other  considerations. 
It  is  usually  more  advisable  to  use  a  storage  battery  for  filament 
lighting  than  any  other  known  source  of  energy. 

21.  May  alternating  current  be  used  for  the  plate  circuit 
of  a  tube? 

Ans.  Never  in  a  receiving  set,  bceause  it  would  be  prac- 
tically impossible  to  eliminate  the  hum  even  with  an  elaborate 
filtering  arrangement.  It  may  be  used  very  satisfactorily  in 
the  case  of  tube  transmitters,  particularly  telegraph  trans- 
mitters. 

22.  May  an  amplifier  be  used  with  a  crystal  detector? 
Ans.    Yes,  providing  the  input  terminals  of  the  amplifier 

are  connected  into  the  circuit  where  the  head-phones  would 
otherwise  be. 

23.  What  is  the  advantage  of  regeneration? 


122  A  B  C  OF  VACUUM  TUBES 

Ans*  It  increases  the  strength  of  the  signals  heard  in  the 
head-phones  by  feeding  back  energy  from  the  plate  to  the 
grid  circuit  and  reinforcing  the  potential  variations  applied 
to  the  grid.  If  the  regeneration  is  great  enough,  local  oscilla- 
tions are  self -generated,  and  undamped  wave  telegraph  signals 
may  be  made  audible  by  the  beat  method. 

24.  What  is  the  disadvantage  of  regeneration  in  the  recep- 
tion of  voice  and  music? 

Ans.  The  delicate  overtones  and  harmonics  are  usually 
lost,  and  if  too  much  regeneration  is  used  the  voice  and  music 
are  distorted. 

25.  What  is  the  squealing  noise  sometimes  heard  with  a 
regenerative  receiver? 

Ans.  It  is  usually  caused  by  too  much  regeneration  and  is 
the  result  of  beat  production  produced  by  oscillations  of 
different  frequencies.  These  oscillations  are  self-generated  in 
the  circuits.  Howling  may  be  caused  by  circuits  being  run 
too  close  to  each  other.  The  wiring  of  plate  and  grid  circuits 
should  be  separated  from  each  other.  Howling  is  often 
caused  by  incorrect  adjustment  of  plate  battery  voltage. 

26.  Is  a  soft  tube  better  than  a  hard  tube  for  a  detector  ? 
Ans.    The  soft  tube  is  more  sensitive,  but  requires  a  very 

critical  adjustment  of  filament  current  and  plate  battery  voltage. 
The  hard  tube  is  somewhat  less  sensitive,  but  is  very  much 
easier  to  maintain  in  adjustment. 

27.  Why  is  it  that  a  whistling  noise  is  sometimes  noticed 
when  receiving  from  a  radio-telephone  station,  no  change  hav- 
ing been  made  in  the  receiver  or  amplifier  adjustments? 

Ans.  This  is  invariably  caused  by  another  station  radiating 
continuous  waves  just  different  enough  from  those  being  re- 
ceded to  produce  a  beat  tone  which  sounds  like  a  whistle. 
Sometimes  these   interfering  oscillations  are  produced  by  a 


QUESTIONS  AND  ANSWERS  123 

nearby  receiving  station  which  is  using  regeneration  and  radiat- 
ing some  of  the  energy,  of  the  locally  generated  oscillations. 

28.  Why  does  placing  the  hands  near  the  panel  of  a 
regenerative  receiver  change  the  signals? 

Ans.  Because  there  is  a  capacity  effect  of  the  body  added 
to  that  of  the  receiver  circuits.  This  changes  the  tuning.  If 
the  receiver  were  properly  shielded  this  effect  would  not  be 
noticed.  Instead  of  shielding,  circuits  are  often  arranged  in 
such  a  manner  as  to  obviate  the  difficulty.  No  properly 
designed  regenerative  receiver  will  give  this  kind  of  trouble. 

29.  How  can  the  "frying"  noise  sometimes  heard  with  a 
soft  detector  tube  be  avoided? 

Ans.    By  never  allowing  the  filament  to  burn  too  brightly. 

30.  Will  one  filament  lighting  battery  be  sufficient  for  a 
vacuum  tube  detector  and  two  stage  amplifier  ? 

Ans.  Yes,  one  storage  battery  of  the  proper  voltage  and 
ampere-hour  capacity  is  all  that  is  required.  The  voltage 
should  be  six  volts  and  the  capacity  either  sixty  or  eighty 
ampere-hours.  The  larger  battery  is  preferable  if  the  receiver 
is  to  be  used  much  and  will  not  have  to  be  charged  as  often  as 
the  smaller.  A  100  ampere-hour  battery  is  not  too  large,  but 
it  is  more  expensive. 

31.  In  a  simple  tube  detector  circuit  (no  regeneration)  why 
is  the  negative  plate  battery  lead  sometimes  connected  to  the 
positive  filament  lead? 

Ans.  The  filament  battery  voltage  adds  somwhat  to  the 
plate  battery  voltage  and  the  plate  potential  is  thereby  increased. 

2,2.  Wliat  is  the  difference  between  a  damped  and  an  un- 
damped wave? 

Ans.  The  amplitudes  of  the  damped  waves  decrease  from 
a  maximum  to  zero  value,  whereas  those  of  an  undamped  wave 
do  not  decrease  but  are  always  the  same. 


i24  A  B  C  OF  VACUUM  TUBES 

33.  What  is  meant  by  a  wave  train  or  group  of  damped 
waves  ? 

Ans.  It  is  a  group  of  oscillations  which  diminish  in  ampli- 
tude to  a  zero  value.  The  amplitudes  diminish  because  they 
are  damped,  that  is  because  energy  is  lost  during  each  reversal 
of  current. 

34.  Why  is  normal  negative  potential  applied  to  the  grid 
of  an  amplifier  tube? 

Ans.  To  avoid  a  grid  current  and  to  bring  the  operating 
point  to  the  straight  portion  of  the  characteristic  curve  with  a 
moderate  value  of  plate  potential.  In  the  case  of  some  tubes  it 
is  not  necessary  to  do  this  if  the  plate  potential  and  filament 
current  are  properly  adjusted. 

35.  Why  is  a  grid  condenser  used  ? 

Ans.  To  avoid  the  use  of  a  grid  battery  or  other  means  of 
fixing  the  normal  grid  potential  and  also  to  operate  the  tube  on 
the  straight  portion  of  the  tube  without  eliminating  the  detector 
action.  The  latter  would  reduce  the  possibility  of  tube  blocking 
because  of  large  grid  potential  amplitude  in  the  negative 
direction. 

36.  Why  is  it  necessary  to  tune  a  receiving  antenna  circuit? 

Ans.  In  order  to  produce  in  it  the  maximum  possible  ampli- 
tudes of  signal  current.  In  other  words,  to  increase  the 
strength  of  the  received  signal. 

37.  Why  is  it  necessary  to  tune  a  secondary  circuit? 

Ans.  To  secure  resonance  between  it  and  the  antenna  circuit 
and  thereby  increase  the  effect  of  the  received  signal  upon  a 
detector.  Also  to  increase  the  selectivity  of  the  receiver,  pro- 
viding the  coupling  is  not  too  great. 

38.  Why  is  it  desirable  to  have  variable  coupling  between 
an  antenna  and  secondary  circuit? 

Ans.    To  vary  the  selectivity  of  the  receiver  and  to  make 


QUESTIONS  AND  ANSWERS  125 

possible  the  elimination  of  unwanted  signals  on  different  wave 
lengths. 

39.  Which  is  better  for  selectivity,  close  or  loose  coupling 
between  the  two  circuits  mentioned? 

Ans.    Loose  coupling. 

40.  When  is  close  coupling  used? 

Ans.  When  it  is  desired  to  stand  by  for  a  call  from  a  trans- 
mitting station  or  to  "pick  up"  a  station  without  knowing  just 
what  adjustments  are  necessary.  The  station  may  be  picked 
up  more  quickly  with  close  coupling.  Also,  when  the  signal 
is  too  weak  to  be  heard  with  loose  coupling. 

41.  May  a  "loud-speaker"  be  used  with  a  crystal  detector 
alone  ? 

Ans.  No,  because  the  energy  is  not  great  enough  to  properly 
operate  it.     The  signal  must  be  amplified  first. 

42.  May  regeneration  be  accomplished  in  a  crystal  detector 
circuit  ? 

Ans.    No,  not  ordinarily.    A  vacuum  tube  is  much  better. 

43.  What  are  ether  waves? 

Ans.  Ether  waves  are  vibrations  in  the  all  pervading 
medium  called  ether.  They  are  quite  similar  to  water  waves 
which  are  vibrations  of  water. 

44.  How  fast  do  ether  waves  travel? 

Ans.  At  the  rate  of  300,000,000  meters  (approx.  186,000 
miles)  per  second. 

45.  Are  ether  waves  only  produced  electrically? 

Ans.  No,  they  may  also  be  produced  by  heat  and  light,  but 
in  these  cases  the  frequencies  of  the  ether  vibrations  are  very 
much  different. 

46.  How  may  the  tubes  of  a  radio- frequency  cascade  ampli- 
fier be  coupled  together? 

Ans.    By  means  of  resistances  or  specially  designed  trans- 


126  ABC  OF  VACUUM  TUBES 

formers.    They  may  also  be  coupled  by  means  of  air  core  choke 
coils  or  air  core  coupling  coils. 

47.  How  may  the  tubes  of  an  audio-frequency  cascade 
amplifier  be  coupled  together? 

Ans.  Usually  by  means  of  iron  core  transformers,  although 
iron  core  reactances  (choke  coils)  may  also  be  used. 

48.  Is  it  advisable  to  operate  a  tube  filament  with  constant 
current  or  constant  voltage? 

Ans.  The  latter  because  the  filament  life  is  thereby  increased. 

49.  How  is  the  filament  current  controlled? 
Ans.    By  means  of  the  filament  rheostat. 

50.  What  effect  upon  the  current  has  an  increase  of  resist- 
ance in  a  circuit? 

Ans.  The  current  decreases  with  increase  of  resistance  pro- 
viding the  E.  M.  F.  is  kept  constant. 

51.  What  are  electrons? 

Ans.  They  are  negative  charges  of  electricity,  the  smallest 
possible  particles  of  negative  electricity.  They  are  also  current 
carriers  when  in  motion  between  two  points  of  different  poten- 
tial in  any  circuit. 

52.  What  happens  when  the  plate  voltage  is  increased  so 
that  it  will  attract  electrons  as  rapidly  as  they  are  emitted  by 
the  filament? 

Ans.  If  the  filament  temperature  is  constant  the  plate  cur- 
rent stops  increasing  no  matter  how  much  more  the  plate 
voltage  is  increased. 

53.  What  happens  when  the  plate  voltage  is  kept  constant 
and  the  filament  temperature  is  gradually  increased? 

Ans.  Up  to  a  certain  value  of  filament  temperature  the 
plate  will  attract  electrons  to  it  as  fast  as  they  are  emitted. 
There  will  come  a  time,  however,  when  the  plate  is  unable  to 
attract  them  at  any  greater  rate  unless  its  voltage  increased. 


QUESTIONS  AND  ANSWERS  127 

Then,  no  matter  what  the  increase  in  filament  temperature,  the 
plate  current  will  not  be  any  further  increased. 

54.  If  the  plate  is  already  attracting  electrons  at  as  great  a 
rate  as  possible  will  an  increase  of  grid  potential  affect  the  plate 
current  ? 

Ans.  No;  because  there  can  be  no  further  increase  in  plate 
current  due  to  attractive  force  exerted  upon  electrons. 

55.  How  is  the  filament  temperature  increased  or  decreased? 
Ans.    By  increasing  or  decreasing  the  filament  current. 

56.  How  is  the  plate  potential  increased  or  decreased, 
regardless  of  the  grid? 

Ans.    By  increasing  of  decreasing  the  plate  battery  voltage. 

57.  Why  is  it  necessary  to  operate  an  amplifier  tube  with 
the  proper  value  of  plate  potential  and  normal  grid  potential? 

Ans.  So  that  the  operating  point  may  be  brought  to  the 
straight  portion  of  the  characteristic  curve  where  equal  varia- 
tions  of  grid  potential  will  produce  proportional  or  symmetrical 
variations  of  plate  current. 

58.  In  this  case  why  may  the  filament  current  not  be  varied  ? 
Ans.    Because,  as  has  been  stated,  it  is  advisable  to  operate 

the  filament  at  a  constant  potential  and  variations  of  any  con- 
sequence should  not  be  made  in  filament  current  unless  they 
result  in  its  reduction. 

59.  Is  it  desirable  to  have  a  step  up  of  voltage  from  primary 
to  secondary  of  an  amplifier  coupling  transformer? 

Ans.  Yes,  this  is  desirable,  and  the  transformer  should  be 
designed  to  operate  best  with  the  particular  tubes  to  be  used. 

60.  What  happens  when  the  plate  battery  voltage  is  in- 
creased too  greatly  without  any  other  changes  being  made  ? 

Ans.  The  normal  plate  current  may  be  made  so  great  that 
saturation  is  reached  and  the  grid  potential  variations  have  no 
effect  upon  it.     Or,  the  operating  point  may  be  upon  the  upper 


128  ABC  OF  VACUUM  TUBES 

bend  of  the  characteristic  curve  and  distortion  may  take  place 
in  the  case  of  amplification.  In  any  event  there  is  considerable 
useless  drain  on  the  plate  battery.  If  the  normal  potential 
of  the  grid  were  made  negative  or  more  negative  the  operating 
point  would  be  brought  lower  and,  with  it,  the  normal  plate 
current. 


INDEX 


"A"  Battery,  43 

Aerial,  31 

Alternating  Current,  19 

Alternating  Current,  Radio  Fre- 
quency, 28 

Ampere,   17 

Amplification,  76 

Amplification,  Audio  Frequency, 
80 

Amplification,   Cascade,  82 

Amplification  Factor,  79 

Amplification,     Radio    Frequency, 

83 

Amplification,  Radio  Frequency 
Regenerative,   85 

Amplifier,  Audio  Frequency,   103 

Amplifier,  Radio  and  Audio  Fre- 
quency, 107 

Amplifier,  Radio  Frequency,  Re- 
sistance Coupled,   104 

Amplifier,  Radio  Frequency, 
Transformer  Coupled,  105 

Amplitude,  28 

Antenna,  31 

Antenna  as  a  Complete  Circuit,  35 

Armstrong  Circuits,  87 

Atom,  71 

Audio  Frequenc}'-,  62 

Audio    Frequency    Amplification, 

8o. 
Audio   Frequency   Amplifier,    103 

Autodyne,  Production  of  Beats,  87 


E 


"B"  Battery,  42 
Battery,  Electrical,  16 
Battery,  Grid,  49 
Battery,   Plate,  42 
Beat,  Zero,  88 
Beats,  74 

Blocking  of  Tube,  68 
By-pass    Condenser,    108 


Coupling,  87 
Coupling,  Capacitive,  91 
Coupling,  Conductive,   91 
Coupling,  Inductive,  91 
Coupling,  Methods  of,  90 
Coupling  Transformer,  80,   105 
Constant,  Dielectric,  24 
Continuous  Oscillations,  28 
Construction    of    Vacuum    Tubes, 

38 
Current,  Alternating,  19 
Current,  Direct,   18 
Current  of  Electricity,  15 
Current,  Pulsating,  19 
Current  Strength,  17 
Cut-off  Potential,  51 
C.    W. —  (Continuous   waves),   97 
Capacity,   22 
Capacitance,  22 
Capacitive  Coupling,  91 
Capacitive  Reactance,  23 
Capacitance,  Tube,  91 
Capacitance,   Variable,  24 
Cascade  Amplification,  82 
Characteristic  Curve,  52 
Choking  of  Tube,  68 
Circuit,  15 
Circuit,  Schematic  for  Production 

of  Beats,  74 
Circuit,  Primary,  90 
Circuit,  Secondary,  90 
Circuit,  Tertiary,   101 
Condenser,  23 
Condenser,  By-pass,   108 
Condenser,  Grid,  66 
Condenser  Effect  in  Antenna,  36 
Conductive  Coupling,  91 


D 


Damped  Oscillations,  29 
Detection,  Simple,  60 
Detection  with  Grid  Condenser,  66 
Detector  Tube,  Gas  Content,  71 


129 


130 


INDEX 


Dielectric,  24 

Dielectric  Constant,  24 

Direct  Current,  18 

Distortion,  Caused  by  Improper 
Grid  Potential,  in 

Distortion,  Caused  by  Overload- 
ing of  Tubes,  113 

Distortion,  Caused  by  Too  Great 
Regeneration,    113 

Distortion,  in  Amplifier  Trans- 
formers, in 

Distortion  in  Amplifier  Tube,  76 

Distortion,  in  Telephone  Receiver, 

114 

E 

Edison  Effect,  42 

Effect  of  Gas  in  a  Detector  Tube, 

7i 
Electrical  Battery,   16 
Electrical  Circuit,  15 
Electrical  Current,  15 
Electrical  Pressure,  17 
Electrical  Resistance,   18 
Electrical  Resonance,  27 
Electro-motive  Force,  17 
Electro-motive    Force,    Pulsating, 

Electro-motive  Force,  Steady'  18 

Electron,  44 

Electron  Emission  from  a  Heated 

Filament,  44 
E.M.F.  (Electro-motive  Force),  17 
Ether,  32 

Ether  Oscillations,  32 
Ether  Vibrations,  32 
Ether  Waves,  32 


Feed-back,  85,  86 
Filament  Battery,  43 
Filament  Construction,  39 
Filament     Current,     Influence    on 

Plate  Current,  47 
Filament  Temperature  Dependant 

Upon  Filament  Current,  43 
Forced  Oscillations,  90 
Frequency,  20 
Frequency,  Audio,  62 
Frequency,  Resonance,  34 
Frequency,  Tone,  65 


Gas  in  a  Detector  Tube*  71 


Grid  Battery,  49 

Grid  Charge,  49 

Grid  Charge,  Leakage  of,  68 

Grid  Condenser,  66 

Grid  Construction,  40 

Grid  Leak  Resistance,  70 

Grid  Potential,  Influence  on  Plate 

Current,  49 
Grid  Variometer,  101 


H 


Heterodyne  Action,  72, 
Heterodyne,  Self,  88 
Heterodyne,  Separate,  73,  88 


I 


Inherent    Amplification,    76 
Inductance,  21 
Inductance,  Loading,  95 
Inductance,  Mutual,  91 
Induction,  30 
Inductive  Coupling,  91 
Inductive  Reactance,  22 
Inter-electrode  Tube  Capacitance, 

91 
Ion,  72 
Ionization,   72 


Leakage,  of  Air  Into  Tube,  42 
Leakage  of  Grid  Charge,  68 
Loading  Inductance,  95 

M 

Modulation,  64 

Methods  of  Coupling,  90 

Mutual  Inductance,  91* 

N 

Normal  Grid  Potential,  56,  82 
Normal  Plate  Current,  53 


O 


Ohm,  18 

Ohm's  Law,  18 

Operation  of  Practical  Circuits,  94 

Operating  Point,  57 

Oscillations,  28 

Oscillations,  Continuous,  28 

Oscillations,  Damped,  29 


INDEX 


131 


Oscillations,  Forced,  90 
Oscillations  in  Ether,  32 
Oscillations,  Undamped,  28 


Plate  Battery,  42 

Plate  Construction,  40 

Plate    Current    Dependent    Upon 

Filament  Current,  47 
Plate    Current    Dependant    Upon 

Grid  Potential,  49 
Plate    Current    Dependant    Upon 

Plate  Potential,  46 
Plate  Current,  Normal,  53 
Plate  Potential,  Influence  on  Plate 

Current,  46 
Plate  Variometer,  101 
Potential,  44 
Fotential,  Negative,  44 
Potential,  Positive,  44 
Practical  Circuits,  94 
Primary  Circuit,  90 
Principle    of    Heterodyne    Action, 

73 
Pulsating  Current,  19 


Q 


Questions  and  Answers,   116 


R 


Radio  Frequencies,  21 
Radio  Frequency  Alternating  Cur- 
rent, 28 
Radio    Frequency    Amplification, 

83 

Radio  Frequency  Amplifier,  Re- 
sistance  Coupled,    104 

Radio  Frequency  Amplifier, 
Transformer   Coupling,    105 

Radio  Frequency  Amplifier  with 
Detector  and  Audio-frequency 
Amplifier,   107 

Radio  Frequency  Regenerative 
Amplification,  85 

Rate  of  Flow  of  Electric  Current, 

17 

Reactance,  21 

Reactance,  Capacitive,  23 

Reactance,  Inductive,  22 

Receiver  for  Weak  Signals,  a  Sug- 
gestion, 109 

Receiver,  Single  Circuit,  No  Re- 
generation, 94 


Receiver,  Single  Circuit,  Regen- 
erative, 96 

Receiver,  Telephone,  59 

Receiver,  Three  Circuit  Regenera- 
tive for  Short  and  Medium 
Waves,  102 

Receiver,  Three  Circuit  Regenera- 
tive for  Short  Waves,  101 

Receiver,  Two  Circuit,  Inductive 
Coupling,  No  Regeneration,  98 

Receiver,  Two  Circuit,  With 
Radio  Frequency  Amplifier,  106 

Receiver,  Two  Circuit,  with  Two 
Stage  Audio  Frequency  Ampli- 
fier, 103 


R 


Receptacles,  42 
Rectification,  53 
Rectification,  Actual,  56 
Rectification,  Apparent,  54 
Regenerative  Amplification,  Radio 

Frequency,  85 
Relay  Action,  52 
Resistance,  18 
Resistance,  Grid  Leak,  70 
Resistance,  Variable,  43 
Resonance,  27 
Resonance  Frequency,  34 
Rheostat,  43 
Rotor,  of  Variometer,  91 


Saturation  Point,  50 

Secondary  Circuit,  90 

Secondary,  Untuned,  95 

Self-heterodyne,  88 

Self-inductance,  21 

Sensitiveness  of  Detector  Tube 
Dependant  on  Applied  Poten- 
tial, 83 

Seperate  Heterodyne,  88 

Simple  Detection,  60 

Single  Circuit  Receiver,  No  Re- 
generation, 94 

Single    Circuit,    Regenerative    Re- 
ceiver, 96 
generative  Receiver,  96 

Space  Charge,   48 

Space  Charge  Effect,  48 

Speed  of  Light,  32 

Sockets,  42 

Stator,   of  Variometer,   91 

Stiffening  a  Circuit,  95 


132 


INDEX 


Telephone  Receiver,  59 

Tertiary  Circuit,  101 

Three  Circuit  Regenerative  Re- 
ceiver for  Short  and  Medium 
Waves,  102 

Three  Circuit  Regenerative  Re- 
ceiver for  Short  Waves,  101 

Tickler,  96 

Tone  Frequency,,  65 

Train  of  Damped  Oscillations,  29 

Transformer  Coupling,  80,  105 

Two  Circuit  Receiver,  Inductive 
Coupling,  No  Regeneration,  98 

Two  Circuit  Receiver  With  Two 
Stage  Audio-frequency  Ampli- 
fier, 103 

Two  Circuit  Regenerative  Re- 
ceiver,   Inductive    Coupling,    100 

Tube  Blocking,  68 

Tube  Capacitance,  91 

Tube  Choking,  68 

Tube  Construction,  38 

Tuning  the  Receiving  Antenna,  33 

U 
Undamped  Oscillations,  28 


Untuned  Secondary,  95 

V 

Vacuum,  38 

Vacuum  Tube,  38 

Vacuum  Tube  Amplifier,  76 

Vacuum  Tube  as   a  Rectifier  and 

Relay,  38 
Vacuum  Tube  Detector,  59 
Variable  Capacitance,  24 
Variable  Resistance,  43 
Variometer,  91 
Variometer,  Grid,  101 
Variometer,  Plate,   101 
Velocity  of  Ether  Waves,  32 
Voice  Distortion,   11 1 
Volt,  18 
Voltage,  18 
Voltage  Amplification  Factor,  79 


W 


Wave  Length,  32 


Zero  Beat, 


LATEST 

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CATALOGUE 

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Practical  and  Mechanical  Books 

Including  Automobile  and  Aviation  Books 


PRACTICAL  BOOKS  FOR  PRACTICAL  MEN 

Each  Book  in  this  Catalogue  is  written  by  an 
Expert  and  is  written  so  you  can  understand  it 


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INDEX 


PAGE 

Abrasives  and  Abrasive  Wheels 29 

Accidents 25 

Air  Brakes 24,  26 

Arithmetic 13,  27,  37 

Automobile  Books 3,  4,  5,  6 

Automobile  Charts 6,7 

Automobile  Ignition  Systems 7 

Automobile  Lighting 4 

Automobile  Questions  and  Answers ....  5 

Automobile  Repairing 5 

Automobile  Starting  Systems 4 

Automobile  Trouble  Charts 6,7 

Automobile  Welding 6 

Aviation 8 

Bells,  Electric 14 

Bevel  Gear 21 

Boats,  Motor 30 

Boiler  Room  Chart 9 

Boilers,  Marine 30 

Brazing 9 

Cams 21 

Carburetion  Trouble  Charts 7 

Carburetors 4 

Car  Charts 9 

Cements 12 

Change  Gear 21 

Charts 6,  7,  9 

Chemistry 10 

Coal 24 

Combustion 19 

Concrete 10,  11,  12 

Concrete  for  Farm  Use 11 

Concrete  for  Shop  Use 11 

Cosmetics 32 

Dictionary 12,  17 

Dies 12 

Drawing 13,  32 

Drawing  for  Plumbers 32 

Dynamo  Building 14 

Electric  BeUs 14 

Electric  Dictionary 17 

Electric  Switchboards 15 

Electric  Toy  Making 16 

Electric  Wiring 15 

Electricity 13,  14,  15,  16,  17,  18 

Electroplating 19 

Encyclopedia 29 

Engine,  Aviation 8 

E-T  Air  Brake 26 

Factory  Management 19 

Ford  Automobile 4 

Ford  Tractor 4 

Ford  Trouble  Chart 7 

Formulas  and  Recipes 34 

Fuel 19 

Gas  Engines , 20,  21 

Gas  Tractor 39 

Gearing  and  Cams 21 

Glossary  Aviation  Terms 8 

Heating 37 

High  Frequency  Apparatus 15 

Horse-Power  Chart 36 

Hot  Water  Heating 37 

House  Wiring 17,18 

Hydraulics 22 

Ice 22 

Ignition  Systems 4 

Ignition  Trouble  Chart 7 

India  Rubber 35 

Interchangeable  Manufacturing 27 

Inventions 22 

Kerosene  Carburetors 4 

Knots 23 


PAGE 

Lathe  Work 23 

Link  Motions 24 

Liquid  Air 24 

Locomotive  Boilers 25 

Locomotive  Breakdowns 25 

Locomotive  Engineering 24,  25,  26 

Machinist  Books 27,  28,  29 

Manual  Training 30 

Marine  Engineering 30 

Marine  Gasoline  Engines 21 

Mechanical  Drawing 13 

Mechanical  Movements 28 

Metal  Work 12 

Model  Making 29 

Motor  Boats 30 

Motorcycles 7,31 

Motor  Truck 3 

Naval  Engineering 30 

Patents 22 

Pattern  Making 31 

Perfumery 32 

Perspective 13 

Plumbing 32,  33 

Punches 12 

Producer  Gas 21 

Questions  and  Answers  on  Automobile .  5 

Questions  on  Heating 38 

Radio  Time  Signal  Receiver 16,  17 

Railroad  Accidents 25 

Railroad  Charts - 9 

Recipe  Book 34 

Refrigeration , 22 

Repairing  Automobiles 5 

Rope  Work 23 

Rubber 35 

Rubber  Stamps 35 

Saw  Filing 35 

Saws,  Management  of 35 

Screw  Cutting 35 

Shipbuilders'  Pocket  Book 30 

Shop  Construction 27 

Shop  Management 27 

Shop  Practice 27,  28,  29 

Shop  Tools 29 

Sketching  Paper 13 

Slide  Valve 24 

Soldering 9 

Splices  and  Rope  Work 23 

Steam  Engineering 35,  36,  37 

Steam  Heating 37 

Steel 38 

Storage  Batteries . 18 

Submarine  Chart 9 

Switchboards 15 

Tapers 23 

Telegraphy,  Wireless   14,  16,  18 

Telephone 18 

Thread-Cutting 27 

Tool  Making 27 

Tool  Steel 38 

Toy  Making . . 16 

Tractive  Power  Chart 9 

Tractor,  Gas 39 

Train  Rules 26 

Vacuum  Heating 38 

Valve  Setting 24 

Ventilation 37 

Walschaert  Valve  Gear 26 

Waterproofing 12 

Welding 6,  39 

Wireless  Telegraphy 14,  16,  18 

Wiring 15,  17,  18 

Wiring  Diagrams 15 


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HOW  TO  REMIT. — By  Postal  Money  Order,  Express  Mones  Ord6r-  Bank  Draft*  *>r  Registered  Letter 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 

AUTOMOBILES 

THE  MODERN    GASOLINE  AUTOMOBILE— ITS    DESIGN,  CONSTRUC- 
TION, MAINTENANCE  AND  REPAIR.     By  Victor  W.  Page,  M.E. 

The  latest  and  most  complete  treatise  on  the  Gasoline  Automobile  ever  issued.  Written 
in  simple  language  by  a  recognized  authority,  familiar  with  every  branch  of  the  auto- 
mobile industry.  Free  from  technical  terms.  Everything  is  explained  so  simply 
that  anyone  of  average  intelligence  may  gain  a  comprehensive  knowledge  of  the 
gasoline  automobile.  The  information  is  up-to-date  and  includes,  in  addition  to  an 
exposition  of  principles  of  construction  and  description  of  all  types  of  automobiles  and 
their  components,  valuable  money-saving  hints  on  the  care  and  operation  of  motor- 
cars propelled  by  internal  combustion  engines.  Among  some  of  the  subjects  treated 
might  be  mentioned:  Torpedo  and  other  symmetrical  body  forms  designed  to  reduce 
air  resistance;  sleeve  valve,  rotary  valve  and  other  types  of  silent  motors;  increasing 
tendency  to  favor  worm-gear  power -transmission:  universal  application  of  magneto 
ignition;  development  of  automobile  electric-lighting  systems;  block  motors;  under- 
slung  chassis;  application  of  practical  self-starters;  long  stroke  and  offset  cylinder 
motors;  latest  automatic  lubrication  systems;  silent  chains  for  valve  operation  and 
change-speed  gearing ;  the  use  of  front  wheel  brakes  and  many  other  detail  refinements. 
By  a  careful  study  of  the  pages  of  this  book  one  can  gain  practical  knowledge  of  auto- 
mobile construction  that  will  save  time,  money  and  worry.  The  book  tells  you  just 
what  to  do,  how  and  when  to  do  it.  Nothing  has  been  omitted,  no  detail  has  been 
slighted.  Every  part  of  the  automobile,  its  equipment,  accessories,  tools,  supplies, 
spare  parts  necessary,  etc.,  have  been  discussed  comprehensively.  If  you  are  or 
intend  to  become  a  motorist,  or  are  in  any  way  interested  in  the  modern  Gasoline 
Automobile,  this  is  a  book  you  cannot  afford  to  be  without.  1032  pages —  and 
more  than  1,000  new  and  specially  made  detail  illustrations,  as  well  as  many  full-page 
and  double-page  plates,  showing  all  parts  of  the  automobile.  Including  12  large 
folding  plates.     New  Edition.     Price         $4.00 

WHAT   IS    SAID    OP   THIS   BOOK: 
"It  is  the  best  book  on  the  Automobile  seen  up  to  date." — J.  H.  Pile,  Associate  Editor 
Automobile  Trade  Journal. 

"Every  Automobile  Owner  has  use  for  a  book  of  this  character." — The  Tradesman. 
"This  book  is  superior  to  any  treatise  heretofore  published  on  the  subject." — The 
Inventive  Age. 

"We  know  of  no  other  volume  that  is  so  complete  in  all  its  departments,  and  in  which 
the  wide  field  of  automobile  construction  with  its  mechanical  intricacies  is  so  plainly 
handled,  both  in  the  text  and  in  the  matter  of  illustrations." — The  Motorist. 
"The  book  is  very  thorough,  a  careful  examination  failing  to  disclose  any  point  in 
connection  with  the  automobile,  its  care  and  repair,  to  have  been  overlooked."— 
Iron  Age. 

"Mr.  Page  has  done  a  great  work,  and  benefit  to  the  Automobile  Field." — W.  O. 
Hasford,  Mgr.  Y.  M.  C.  A.  Automobile  School,  Boston,  Mass. 

"It  is  just  the  kind  of  a  book  a  motorist  needs  if  he  wants  to  understand  his  car."— 
American  Thresherman. 

THE  MODERN  MOTOR  TRUCK,  ITS  DESIGN,  CONSTRUCTION,  OPERA- 
TION AND  REPAIR.     By  Victor  W.  Page. 

Just  off  the  press  and  treats  on  all  types  of  motor  trucks  and  industrial  tractors  and 
trailers.  It  considers  all  types  of  trucks,  gasoline  and  electric,  and  all  varieties  of 
truck  bodies.  This  book  is  written  in  language  everyone  can  understand  and  is 
not  in  any  sense  of  the  word  a  technical  treatise.  It  is  a  practical  volume  that  will 
make  special  appeal  to  the  truck  driver  who  seeks  to  better  his  position  and  to  the 
mechanic  charged  with  the  repair  and  upkeep  of  trucks.  The  factory  or  business 
executive  who  wants  to  obtain  a  complete  working  knowledge  of  truck  operation 
problems  will  find  this  book  a  reference  work  of  great  value.  The  truck  salesman  or 
automobile  dealer  will  find  that  this  work  contains  information  that  means  money 
to  them.  All  garage  and  service  station  men  should  have  a  copy  of  this  book  for 
reference  because  truck  construction  differs  from  passenger  car  design  in  many  im- 
portant respects.  Anyone  who  reads  this  book  is  in  touch  with  all  the  practical 
features  that  have  been  tested  out  in  real  service.  1921  Edition.  Cloth,  6x9, 
962  pages,  750  illustrations     Price $5.00 

3 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 

THE  MODEL  T  FORD  CAR,  ITS  CONSTRUCTION,  OPERATION  AND 
REPAIR,  INCLUDING  THE  FORDSON  FARM  TRACTOR,  F.  A.  LIGHT- 
ING AND  STARTING  SYSTEM,  FORD  MOTOR  TRUCK.  By  Victor 
W.  Page. 

This  is  the  most  complete  and  practical  instruction  book  ever  published  on  the  Ford 
car  and  Fordson  tractor.  All  parts  of  the  Ford  Model  T  car  and  Fordson  tractor 
are  described  and  illustrated  in  a  comprehensive  manner.  The  construction  is 
fully  treated  and  operating  principle  made  clear  to  everyone.  Complete  instructions 
for  driving  and  repairing  are  given.  To  the  New  Revised  Edition  matter  has  been 
added  on  the  Ford  Truck  and  Tractor  Conversion  Sets  and  Genuine  Fordson  Tractor. 
All  parts  are  described.  All  repair  processes  illustrated  and  fully  explained.  "Written 
so  all  can  understand — no  theory,  no  guesswork.  New  revised  and  enlarged  Edition 
just  published.     153  illustrations,  410  pages,  2  large  folding  plates.     Price     .     $2.00 

AUTOMOBILE  STARTING,  LIGHTING  AND  IGNITION  SYSTEMS.  By 
Victor  W.  Page,  M.E. 

This  practical  volume  has  been  written  with  special  reference  to  the  requirements  of  the 
non-technical  reader  desiring  easily  understood,  explanatory  matter,  relating  to  all 
types  of  automobile  ignition,  starting  and  lighting  systems.  It  can  be  understood  by 
anyone,  even  without  electrical  knowledge,  because  elementary  electrical  principles  are 
considered  before  any  attempt  is  made  to  discuss  features  of  the  various  systems. 
These  basic  principles  are  clearly  stated  and  illustrated  with  simple  diagrams.  All  the 
leading  systems  of  starting,  lighting  and  ignition  have  been  described  and  illustrated  with 
the  co-operation  of  the  experts  employed  by  the  manufacturers.  Wiring  diagrams  are 
shown  in  both  technical  and  non-technical  forms.  All  symbols  are  fully  explained.  It 
is  a  comprehensive  review  of  modern  starting  and  ignition  system  practice,  and  includes 
a  complete  exposition  of  storage  battery  construction,  care  and  repair.  All  types  of 
starting  motors,  generators,  magnetos,  and  all  ignition  or  lighting  system  units  are 
fully  explained.  The  systems  of  cars  already  in  use  as  well  as  those  that  are  to  come 
are  considered.  Every  person  in  the  automobile  business  needs  this  volume.  5Mx7>£. 
Cloth.  815  pages,  492  illustrations,  3  folding  plates.  New  revised  and  enlarged 
edition.     Price $3.00 

GASOLINE  AND  KEROSENE  CARBURETORS,  CONSTRUCTION,  IN- 
STALLATION AND  ADJUSTMENT.  By  Victor  W.  Page.  A  new  up- 
to-date  Book  on  Modern  Carburetion  Practice. 

This  is  a  simple,  comprehensive,  and  authoritative  treatise  for  practical  men  ex- 
plaining all  basic  principles  pertaining  to  carburetion,  showing  how  liquid  fuels  are 
vaporized  and  turned  into  gas  for  operating  all  types  of  internal  combustion  engines  in- 
tended to  operate  on  vapors  of  gasoline,  kerosene,  benzol,  and  alcohol.  All  leading  types 
of  carburetors  are  described  in  detail,  special  attention  being  given  to  the  forms  devised 
to  use  the  cheaper  fuels  such  as  kerosene.  Carburetion  troubles,  fuel  system  troubles, 
carburetor  repairs  and  installation,  electric  primers  and  economizers,  hot  spot  mani- 
folds and  all  modern  carburetor  developments  are  considered  in  a  thorough  manner. 
Methods  of  adjusting  all  types  of  carburetors  are  fully  discussed  as  well  as  sugges- 
tions for  securing  maximum  fuel  economy  and  obtaining  highest  engine  power. 
This  book  is  invaluable  to  repairmen,  students,  and  motorists,  as  it  includes  the 
most  complete  exposition  on  kerosene  carburetors  ever  published.  The  drawings 
showing  carburetor  construction  are  made  from  accurate  engineering  designs  and 
show  all  parts  of  late  types  of  carburetors.     213  pages.     89  illustrations.   .      $2.00 

HINTS  AND  TIPS  FOR  AUTOMOBILISTS.    By  Victor  W.  Page. 

The  book  is  ideal  for  the  busy  man  or  woman  who  wants  to  know  about  car  operation 
and  upkeep  because  of  the  economies  possible  when  an  automobile  is  intelligently 
operated.  It  contains  many  money-saving  hints  and  a  brief  simple  exposition  of 
location  and  remedy  of  roadside  troubles  apt  to  occur  under  ordinary  operating 
conditions.     Price 75  cents 


CATALOGUE   OF  GOOD,  PRACTICAL  BOOKS 

AUTOMOBILE  REPAIRING  MADE  EASY.    By  Victor  W.  Page,  M.E. 

A  comprehensive,  practical  exposition  of  every  phase  of  modern  automobile  repairing 
practice.  Outlines  every  process  incidental  to  motor  car  restoration.  Gives  plans  for 
workshop  construction,  suggestions  for  equipment,  power  needed,  machinery  and  tools 
necessary  to  carry  on  the  business  successfully.  Tells  how  ±o  overhaul  and  repair  all 
parts  of  all  automobiles.  Everything  is  explained  so  simply  that  motorists  and  students 
can  acquire  a  full  working  knowledge  of  automobile  repairing.  This  work  starts  with 
the  engine,  then  considers  carburetion,  ignition,  cooling  and  lubrication  systems.  The 
clutch,  change-speed  gearing  and  transmission  system  are  considered  in  detail.  Contains 
instructions  for  repairing  all  types  of  axles,  steering  gears  and  other  chassis  parts. 
Many  tables,  short  cuts  in  figuring  and  rules  of  practice  are  given  for  the  mechanic. 
Explains  fully  valve  and- magneto  timing,  "tuning"  engines,  systematic  location  of 
trouble,  repair  of  ball  and  roller  bearings,  shop  kinks,  first  aid  to  injured  and  a  multi- 
tude of  subjects  of  interest  to  all  in  the  garage  and  repair  business. 

This  book  contains  special  instructions  on  electric  starting,  lighting  and  ignition  systems, 
tire  repairing  and  rebuilding,  autogenous  welding,  brazing  and  soldering,  heat  treatment  of 
steel,  latest  timing  practice,  eight  and  twelve-cylinder  motors,  etc.  5Mx8.  Cloth.  1060 
pages,  1,000  illustrations,  11  folding  plates.    Price $4.00 

WHAT  IS  SAID  OP  THIS  BOOK : 

*'  'Automobile  Repairing  Made  Easy'  is  the  best  book  on  the  subject  I  have  ever  seen 
and  the  only  book  I  ever  saw  that  is  of  any  value  in  a  garage." — Fred  Jeffrey,  Martins- 
burg,  Neb. 

"I  wish  to  thank  you  for  sending  me  a  copy  of  'Automobile  Repairing  Made  Easy/  I 
do  not  think  it  could  be  excelled." — S.  W.  Gisriel,  Director  of  Instruction,  Y.  M.  C.  A., 
Philadelphia,  Pa. 

QUESTIONS  AND  ANSWERS  RELATING  TO   MODERN  AUTOMOBILE 
CONSTRUCTION,  DRIVING  AND  REPAIR.    By  Victor  W.  Page,  M.E. 

A  practical  self-instructor  for  students,  mechanics  and  motorists,  consisting  of  thirty- 
seven  lessons  in  the  form  of  questions  and  answers,  written  with  special  reference  to  the 
requirements  of  the  non-technical  reader  desiring  easily  understood,  explanatory 
matter  relating  to  all  branches  of  automobiling.  The  subject-matter  is  absolutely 
correct  and  explained  in  simple  language.  If  you  can't  answer  all  of  the  following 
questions,  you  need  this  work.  The  answers  to  these  and  nearly  2000  more  are  to 
be  found  in  its  pages.  Give  the  name  of  all  important  parts  of  an  automobile  and 
describe  their  functions?  Describe  action  of  latest  types  of  kerosene  carburetors? 
What  is  the  difference  between  a  "double"  ignition  system  and  a  "dual"  ignition 
system?  Name  parts  of  an  induction  coil?  How  are  valves  timed?  What  is  an 
electric  motor  starter  and  how  does  it  work?  What  are  advantages  of  worm  drive 
gearing?  Name  all  important  types  of  ball  and  roller  bearings?  What  is  a  "  three- 
quarter"  floating  axle?  What  is  a  two-speed  axle?  What  is  the  Vulcan  electric  gear 
shift?  Name  the  causes  of  lost  power  in  automobiles?  Describe  all  noises  due  to 
deranged  mechanism  and  give  causes?  How  can  you  adjust  a  carburetor  by  the 
color  of  the  exhaust  gases?  What  causes  "popping"  in  the  carburetor?  What  tools 
and  supplies  are  needed  to  equip  a  car?  How  do  you  drive  various  makes  of  cars? 
What  is  a  differential  lock  and  where  is  it  used?  Name  different  systems  of  wire 
wheel  construction,  etc.,  etc.  A  popular  work  at  a  popular  price.  5^x7^.  Cloth. 
701  pages,  387  illustrations,  3  folding  plates.      New  revised  edition.     Price  $2.50 

WHAT  IS  SAID  OP  THIS  BOOK: 
"If  you  own  a  car — get  this  book." — The  Glassworker. 

"Mr.  Page  has  the  faculty  of  making  difficult  subjects  plain  and  understandable." — 
Bristol  Press. 

"We  can  name  no  writer  better  qualified  to  prepare  a  book  of  instruction  on  auto- 
mobiles than  Mr.  Victor  W.  Page." — Scientific  American. 

"The  best  automobile  catechism  that  has  appeared." — Automobile  Topics. 

"  There  are  few  men,  even  with  long  experience,  who  will  not  find  tbis  book  useful. 
Great  pains  have  been  taken  to  make  it  accurate.  Special  recommendation  must  be 
given  to  the  illustrations,  which  have  been  made  specially  for  the  work.  Such  ex- 
cellent books  as  this  greatly  assist  in  fully  understanding  your  automobile." — En- 
gineering News. 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 

HOW  TO  RUN  AN  AUTOMOBILE.     By  Victor  W.  Page. 

This  treatise  gives  concise  instructions  for  starting  and  running  all  makes  of  gasoline 
automobiles,  how  to  care  for  them,  and  gives  distinctive  features  of  control.  De- 
scribes every  step  for  shifting  gears,  controlling  engine,  etc.  Among  the  chapters 
contained  are:  I.  Automobile  Parts  and  Their  Functions.  II.  General  Starting 
and  Driving  Instructions.  III.  Control  Systems — Care  of  Automobiles.  Thoroughly 
illustrated.     178  pages.    72  illustrations.      Price $1.50 

THE  AUTOMOBILISTS  POCKET  COMPANION  AND  EXPENSE  RECORD* 
By  Victor  W.  Page. 

This  book  is  not  only  valuable  as  a  convenient  cost  record,  but  contains  much  in- 
formation of  value  to  motorists.  Includes  a  condensed  digest  of  auto  laws  of  all 
States,  a  lubrication  schedule,  hints  for  care  of  storage  battery,  and  care  of  tires, 
location  of  road  troubles,  anti-freezing  solutions,  horse-power  table,  driving  hints 
and  many  useful  tables  and  recipes  of  interest  to  all  motorists.  Not  a  technical 
book  in  any  sense  of  the  word,  just  a  collection  of  practical  facts  in  simple  language 
for  the  every-day  motorist.     Convenient  pocket  size.     Price $1.50 

AUTOMOBILE    WELDING    WITH  THE  OXY-ACETYLENE  FLAME.     By 

M.  Keith  Dunham. 

Explains  in  a  simple  manner  apparatus  to  be  used,  its  care,  and  how  to  construct 
necessary  shop  equipment.  Proceeds  then  to  the  actual  welding  of  all  automobile 
parts,  in  a  manner  understandable  by  everyone.  Gives  principles  never  to  be  for- 
gotten. This  book  is  of  utmost  value,  since  the  perplexing  problems  arising  when 
metal  is  heated  to  a  melting  point  are  fully  explained  and  the  proper  methods  to 
overcome  them  shown.     167  pages.    Fully  illustrated.     Price $1.50 


UTOMOBILE,  AVIATION  AND  MOTORCYCLE  CHARTS 

AVIATION  CHART— LOCATION  OF  AIRPLANE  POWER  PLANT  TROUBLES 
MADE  EASY.    By  Major  Victor  W.  Page,  A.S.,  S.C.U.S.R. 

A  large  chart  outlining  all  parts  of  a  typical  airplane  power  plant,  showing  the  points 
where  trouble  is  apt  to  occur  and  suggesting  remedies  for  the  common  defects.  In- 
tended especially  for  aviators  and  aviation  mechanics  on  school  and  field  duty. 
Price 35  cents 

CHART.  GASOLINE  ENGINE  TROUBLES  MADE  EASY— A  CHART  SHOW- 
ING SECTIONAL  VIEW  OF  GASOLINE  ENGINE.  Compiled  by  Victor 
W.  Page,  M.E. 

It  shows  clearly  all  parts  of  a  typical  four-cylinder  gasoline  engine  of  the  four-cycle 
type.  It  outlines  distinctly  all  parts  liable  to  give  trouble  and  also  details  the  de- 
rangements apt  to  interfere  with  smooth  engine  operation. 

Valuable  to  students,  motorists,  mechanics,  repairmen,  garagemen,  automobile  sales- 
men, chauffeurs,  motorboat  owners,  motor-truck  and  tractor  drivers,  aviators,  motor- 
cyclists, and  all  others  who  have  to  do  with  gasoline  power  plants. 
It  simplifies  location  of  all  engine  troubles,  and  while  it  will  prove  invaluable  to  the 
novice,  it  can  be  used  to  advantage  by  the  more  expert.  It  should  be  on  the  walls  of 
every  public  and  private  garage,  automobile  repair  shop,  clubhouse  or  school.  It  can 
be  carried  in  the  automobile  or  pocket  with  ease,  and  will  insure  against  loss  of  time 
when  engine  trouble  manifests  itself. 

This  sectional  view  of  engine  is  a  complete  review  of  all  motor  troubles.  It  is  prepared 
by  a  practical  motorist  for  all  who  motor.  More  information  for  the  money  than  ever 
before  offered.  No  details  omitted.  Size  25x38  inehes.  Securely  mailed  on  receipt 
of 35  cents 


CATALOGUE   OF  GOOD,  PRACTICAL  BOOKS 

CHART.    LOCATION  OF  FORD  ENGINE  TROUBLES  MADE  EASY.    Com- 
piled by  Victor  W.  Page,  M.E. 

This  shows  clear  sectional  views  depicting  all  portions  of  the  Ford  power  plant  and 
auxiliary  groups.  It  outlines  clearly  all  parts  of  the  engine,  fuel  supply  system,  igni- 
tion group  and  cooling  system,  that  are  apt  to  give  trouble,  detailing  all  derangements 
that  are  liable  to  make  an  engine  lose  power,  start  hard  or  work  irregularly.  This 
chart  is  valuable  to  students,  owners,  and  drivers,  as  it  simplifies  location  of  all  engine 
faults.  Of  great  advantage  as  an  instructor  for  the  novice,  it  can  be  used  equally  well 
by  the  more  expert  as  a  work  of  reference  and  review.  It  can  be  carried  in  the  tool- 
box or  pocket  with  ease  and  will  save  its  cost  in  labor  eliminated  the  first  time  engine 
trouble  manifests  itself.  Prepared  with  special  reference  to  the  average  man's  needs 
and  is  a  practical  review  of  all  motor  troubles  because  it  is  based  on  the  actual  ex- 
perience of  an  automobile  engineer-mechanic  with  the  mechanism  the  chart  describes. 
It  enables  the  non-technical  owner  or  operator  of  a  Ford  car  to  locate  engine  de- 
rangements by  systematic  search,  guided  by  easily  recognized  symptoms  instead  of  by 
guesswork.  It  makes  the  average  owner  independent  of  the  roadside  repair  shop 
when  touring.  Must  be  seen  to  be  appreciated.  Size  25x38  inches.  Printed  on 
heavy  bond  paper.    Price 35  cents 

CHART.    LUBRICATION  OF  THE  MOTOR  CAR  CHASSIS.     Compiled  by 
Victor  W.  Page,  M.E. 

This  chart  presents  the  plan  view  of  a  typical  six-cylinder  chassis  of  standard  design 
and  all  parts  are  clearly  indicated  that  demand  oil,  also  the  frequency  with  which  they 
must  be  lubricated  and  the  kind  of  oil  to  use.  A  practical  chart  for  all  interested  in 
motor-car  maintenance.     Size  24x38  inches.     Price 35  cents 

CHART.     LOCATION  OF  CARBURETION  TROUBLES  MADE  EASY.    Com- 
piled by  Victor  W.  Page,  M.E. 

This  chart  shows  all  parts  of  a  typical  pressure  feed  fuel  supply  system  and  gives 
causes  of  trouble,  how  to  locate  defects  and  means  of  remedying  them.  Size  24x38 
inches.    Price 35  cents 

CHART.    LOCATION  OF  IGNITION  SYSTEM  TROUBLES  MADE  EASY. 

Compiled  by  Victor  W.  Page,  M.E. 

In  this  diagram  all  parts  of  a  typical  double  ignition  system  using  battery  and  magneto 
current  are  shown,  and  suggestions  are  given  for  readily  finding  ignition  troubles  and 
eliminating  them  when  found.     Size  24x38  inches.     Price 35  cents 

CHART.    LOCATION  OF  COOLING  AND  LUBRICATION  SYSTEM  FAULTS. 
Compiled  by  Victor  W.  Page,  M.E. 

This  composite  diarijram  shows  a  typical  automobile  power  plant  using  pump  circulated 
water-cooling  system  and  the  most  popular  lubrication  method.  Gives  suggestions 
for  curing  all  overhearing  and  loss  of  power  faults  due  to  faulty  action  of  the  oiling 
or  cooling  group.     Size  24x38  inches.    Price 35  cents 

CHART.     LOCATION  OF  STARTING  AND  LIGHTING  SYSTEM  FAULTS. 

The  most  complete  chart  yet  devised,  showing  all  parts  of  the  modern  automobile 
starting,  fighting  and  ignition  systems,  giving  instructions  for  systematic  location  of 
all  faults  in  wiring,  lamps,  motor  or  generator,  switches  and  all  other  units.  Invalu- 
able to  motorists,  chauffeurs  and  repairmen.     Size  24x38  inches.     Price     .     35  cents 

CHART.     MOTORCYCLE  TROUBLES  MADE  EASY.    Compiled  by  Victor 
W.  Page,  M.E. 

A  chart  showing  sectional  view  of  a  single-cylinder  gasoline  engine.  This  chart 
simplifies  location  of  all  power-plant  troubles.  A  single-cylinder  motor  is  shown  for 
simplicity.  It  outlines  distinctly  all  parts  liable  to  give  trouble  and  also  details  the 
derangements  apt  to  interfere  with  smooth  engine  operation.  This  chart  will  prove 
of  value  to  all  who  have  to  do  with  the  operation,  repair  or  sale  of  motorcycles.  No 
details  omitted.     Size  30x20  inches.     Price 35  cents 


CATALOGUE   OF  GOOD,   PRACTICAL  BOOKS 


AVIATION 

A  B  C  OF  AVIATION.    By  Major  Victor  W.  Page\ 

This  book  describes  the  basic  principles  of  aviation,  tells  how  a  balloon  or  dirigible 
is  made  and  why  it  floats  in  the  air.  Describes  how  an  airplane  flies.  It  shows  in 
detail  the  different  parts  of  an  airplane,  what  they  are  and  what  they  do.  Describes 
all  types  of  airplanes  and  how  they  differ  in  construction;  as  well  as  detailing  the 
advantages  and  disadvantages  of  different  types  of  aircraft.  It  includes  a  complete 
dictionary  of  aviation  terms  and  clear  drawings  of  leading  airplanes.  The  reader 
will  find  simple  instructions  for  unpacking,  setting  up,  and  rigging  airplanes.  A 
full  description  of  airplane  control  principles  is  given  and  methods  of  flying  are  dis- 
cussed at  length. 

This  book  answers  every  question  one  can  ask  about  modern  aircraft,  their  con- 
struction and  operation.  A  self-educator  on  aviation  without  an  equal.  274  pages. 
130  specially  made  illustrations  with  7  plates.     Price $2.50 

AVIATION  ENGINES— DESIGN;  CONSTRUCTION;  REPAIR.  By  Major 
Victor  W.  Page,  A.S.,  S.C.U.S.R. 

This  treatise,  written  by  a  recognized  authority  on  all  of  the  practical  aspects  of 
internal  combustion  engine  construction,  maintenance,  and  repair,  fills  the  need  as 
no  other  book  does.  The  matter  is  logically  arranged;  all  descriptive  matter  is 
simply  expressed  and  copiously  illustrated,  so  that  anyone  can  understand  airplane 
engine  operation  and  repair  even  if  without  previous  mechanical  training.  This 
work  is  invaluable  for  anyone  desiring  to  become  an  aviator  or  aviation  mechanic. 
The  latest  rotary  types,  such  as  the  Gnome  Monosoupape,  and  LeRhone,  are  fully 
explained,  as  well  as  the  recently  developed  Vee  and  radial  types.  The  subjects 
of  carburetion,  ignition,  cooling,  and  lubrication  also  are  covered  in  a  thorough  manner. 
The  chapters  on  repair  and  maintenance  are  distinctive  and  found  in  no  other  book 
on  this  subject.  Not  a  technical  book,  but  a  practical,  easily  understood  work  of 
reference  for  all  interested  in  aeronautical  science.  589  pages.  253  illustrations. 
Price,  net $3.00 

GLOSSARY  OF  AVIATION  TERMS  — ENGLISH-FRENCH;  FRENCH- 
ENGLISH.  By  Major  Victor  W.  Page,  A.S.,  S.C.U.S.R.,  and  Lieut. 
Paul  Montariol,  of  the  French  Flying  Corps. 

A  complete  glossary  of  practically  all  terms  used  in  aviation,  having  lists  in  both 
French  and  English  with  equivalents  in  either  language.         Price,  net  .      .      $1.00 

APPLIED  AERODYNAMICS.     By  G.  P.  Thompson. 

This  is  a  scientific  and  mathematical  treatise  that  has  a  special  appeal  to  the  student 
and  engineer  who  are  seeking  exact  information  on  the  aerodynamics  of  heavier-than- 
air  craft  and  data  on  airplane  design  testing.  This  book  gives  an  up-to-date  presen- 
tation of  the  existing  state  of  Aeronautical  Science.  In  addition  to  a  very  full  diL 
cussion  of  the  qualities  which  determine  the  speed  and  rate  of  climb  of  an  aeroplane 
and  the  method  by  which  they  can  be  calculated,  special  attention  is  paid  to  stability 
— a  problem  now  fairly  well  understood,  and  to  controllability — our  knowledge  of 
which  is  at  present  in  a  much  more  elementary  state.  Attention  is  directed  to  the 
numerous  directions  in  which  further  information  is  required,  especially  in  the  form  of 
full-scale  experiments.  312  pages  (7  x  10).  Illustrated  with  over  142  Diagrams 
and  Graphic  Charts.     Price $12.50 

AVIATION  CHART— LOCATION  OF  AIRPLANE  POWER  PLANT  TROUBLES 
MADE  EASY.     By  Major  Victor  W.  Page,  A.S.,  S.C.U.S.R. 

A  large  chart  outlining  all  parts  of  a  typical  airplane  power  plant,  showing  the  points 
where  trouble  is  apt  to  occur  and  suggesting  remedies  for  the  common  defects.  In- 
tended especially  for  aviators  and  aviation  mechanics  on  school  and  field  duty. 
Price 35  cents 

8 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 


BRAZING  AND  SOLDERING 

BRAZING  AND  SOLDERING.     By  James  F.  Hobart. 

The  only  book  that  shows  you  just  how  to  handle  any  job  of  brazing  or  soldering  that 
conies  along ;  it  tells  you  what  mixture  to  use,  how  to  make  a  furnace  if  you  need  one. 
Full  of  valuable  kinks.  The  fifth  edition  of  this  book  has  just  been  published,  and  to 
it  much  new  matter  and  a  large  number  of  tested  formulae  for  all  kinds  of  solders  and 
fluxes  have  been  added.     Illustrated.  . 35   cents 

SOLDERING  AND  BRAZING.    By  Raymond  Francis  Yates. 

This  treatise  gives  all  the  necessary  "kinks"  that  will  enable  one  to  accomplish  suc- 
cessful soldering.  If  a  mechanic  has  not  succeeded  in  his  soldering,  this  book  may 
tell  him  just  what  he  needs  to  produce  good  work — something  that  he  may  hereto- 
fore have  forgotten.     Price 75  cents 


CHARTS 

MODERN  SUBMARINE  CHART. 

A  cross-section  view,  showing  clearly  and  distinctly  all  the  interior  of  a  Submarine  of 
the  latest  type.  You  get  more  information  from  this  chart,  about  the  construction  and 
operation  of  a  Submarine,  than  in  any  other  way.  No  details  omitted — everything 
is  accurate  and  to  scale.  All  the  machinery  and  devices  fitted  in  a  modern  Submarine 
Boat  are  shown 35  cents 

BOX  CAR  CHART. 

A  chart  showing  the  anatomy  of  a  box  car,  having  every  part  of  the  car  numbered  and 
its  proper  name  given  in  a  reference  list 35  cent* 

GONDOLA  CAR  CHART. 

A  chart  showing  the  anatomy  of  a  gondola  car,  having  every  part  of  the  car  numbered 
and  its  proper  reference  name  given  in  a  reference  list 35   cents 

PASSENGER-CAR  CHART. 

A  chart  showing  the  anatomy  of  a  passenger-car,  having  every  part  of  the  car  numbered 
and  its  proper  name  given  in  a  reference  list 35  cents 

STEEL  HOPPER  BOTTOM  COAL  CAR. 

A  chart  showing  the  anatomy  of  a  steel  Hopper  Bottom  Coal  Car,  having  every  part 
of  the  car  numbered  and  its  proper  name  given  in  a  reference  list 35  cents 

TRACTIVE  POWER  CHART. 

A  chart  whereby  you  can  find  the  tractive  power  or  drawbar  pull  of  any  locomotive 
without  making  a  figure.  Shows  what  cylinders  are  equal,  how  driving  wheels  and 
steam  pressure  affect  the  power.  What  sized  engine  you  need  to  exert  a  given  drawbar 
puU  or  anything  you  desire  in  this  line. 50  cents 

HORSE-POWER  CHART 

Shows  the  horse-power  of  any  stationary  engine  without  calculation.  No  matter  what 
the  cylinder  diameter  of  stroke,  the  steam  pressure  of  cut-off,  the  revolutions,  or 
whether  condensing  or  non-condensing,  it's  all  there.  Easy  to  use,  accurate,  and 
saves  time  and  calculations.     Especially  useful  to  engineers  and  designers.     50  cents 

BOILER  ROOM  CHART.     By  Geo.  L.  Fowler. 

A  chart — size  14x28  inches — showing  in  isometric  perspective  the  mechanisms  be- 
longing in  a  modern  boiler  room.  The  various  parts  are  shown  broken  or  removed, 
so  that  the  internal  construction  is  fully  illustrated.  Each  part  is  given  a  reference 
number,  and  these,  with  the  corresponding  name,  are  given  in  a  glossary  printed  at 
the  sides 35  centi 

9 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 


CHEMISTRY 

HOW  TO  MAKE  AND  USE  A  SMALL  CHEMICAL  LABORATORY.     By 

Raymond  Francis  Yates. 

The  treatise  covers  all  of  the  essentials  of  elementary  chemistry.  The  law  ©f  definite 
proportions,  solutions,  crystalloids,  colloids,  electrolysis,  etc.,  are  explained.  The 
second  part  of  the  book  is  devoted  to  chemical  and  electro-chemical  experiments. 
Only  those  experiments  that  will  tend  to  broaden  the  reader's  knowledge  of  chemistry 
in  general  have  been  chosen.     Price 75  cents 


CONCRETE 

JUST   PUBLISHED— CONCRETE   WORKERS'   REFERENCE   BOOKS.      A 

SERIES     OF    POPULAR     HANDBOOKS    FOR     CONCRETE     USERS. 

Prepared  by  A.  A.  Houghton Each  75  cents 

The  author,  in  preparing  this  Series,  has  not  only  treated  on  the  usual  types  of  construction, 
but  explains  and  illustrates  molds  and  systems  that  are  not  patented,  but  which  are  equal 
in  value  and  often  superior  to  those  restricted  by  patents.  These  molds  are  very  easily  and 
cheaply  constructed  and  embody  simplicity,  rapidity  of  operation,  and  the  most  successful 
results  in  the  molded  concrete.  Each  of  these  Twelve  books  is  fully  illustrated,  and  the 
subjects  are  exhaustively  treated  in  plain  English. 

CONCRETE  WALL  FORMS.    By  A.  A.  Houghton. 

A  new  automatic  wall  clamp  is  illustrated  with  working  drawings.     Other  types  ol 

wall  forms,   clamps,   separators,   etc.,   are  also  illustrated  and  explained. 

(No.  1  of  Series) 75  cents 

CONCRETE  FLOORS  AND  SIDEWALKS.    By  A.  A.  Houghton. 

The  molds  for  molding  squares,  hexagonal  and  many  other  styles  of  mosaic  floor  and 
sidewalk  blocks  are  fully  illustrated  and  explained.     (No.  2  of  Series)     .     .     75  cents 

PRACTICAL  CONCRETE  SILO  CONSTRUCTION.    By  A.  A.  Houghton. 

Complete  working  drawings  and  specifications  are  given  for  several  styles  of  concrete 
silos,  with  illustrations  of  molds  for  monolithic  and  block  silos.  The  tables,  data,  and 
information  presented  in  this  book  are  of  the  utmost  value  in  planning  and  constructing 
all  forms  of  concrete  silos.     (No.  3  of  Series) 75   cents 

MOLDING  CONCRETE  CHIMNEYS,  SLATE  AND  ROOF  TILES.    By  A.  A. 

Houghton. 

The  manufacture  of  all  types  of  concrete  slate  and  roof  tile  is  fully  treated.  Valuable 
data  on  all  forms  of  reinforced  concrete  roofs  are  contained  within  its  pages.  The 
construction  of  concrete  chimneys  by  block  and  monolithic  systems  is  fully  illustrated 
and  described.  A  number  of  ornamental  designs  of  chimney  construction  with  molds 
are  shown  in  this  valuable  treatise.     (No.  4  of  Series.) 75  cents 

MOLDING  AND  CURING  ORNAMENTAL  CONCRETE.    By  A.  A.  Houghton. 

The  proper  proportions  of  cement  and  aggregates  for  various  finishes,  also  the  method 
of  thoroughly  mixing  and  placing  in  the  molds,  are  fully  treated.  An  exhaustive 
treatise  on  this  subject  that  every  concrete  worker  will  find  of  daily  use.  and  value 
(No.  5  of  Series.) 75  cents 

CONCRETE  MONUMENTS,  MAUSOLEUMS^AND  BURIAL  VAULTS.    By 
A.  A.  Houghton. 

The  molding  of  concrete  monuments  to  imitate  the  most  expensive  cut  stone  is  ex- 
plained in  this  treatise,  with  working  drawings  of  easily  built  molds.  Cutting  in- 
scriptions and  designs  are  also  fully  treated.     (No.  6  of  Series.)       ...     75  cents 

10 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 

MOLDING  CONCRETE  BATHTUBS,  AQUARIUMS  AND  NATATORIUMS. 
By  A.  A.  Houghton. 

Simple  molds  and  instruction  are  given  for  molding  many  styles  of  concrete  oath  tubs, 
swimming-pools,  etc.  These  molds  are  easily  built  and  permit  rapid  and  successful 
work.     (No.  7  of  Series.) 75   cents 

CONCRETE  BRIDGES,  CULVERTS  AND  SEWERS.    By  A.  A.  Houghton. 

A  number  of  ornamental  concrete  bridges  with  illustrations  of  molds  are  given.  A 
collapsible  center  or  core  for  bridges,  culverts  and  sewers  is  fully  illustrated  with  de» 
tailed  instructions  for  building.     (No.  8  of  Series.) 75  cents 

CONSTRUCTING  CONCRETE  PORCHES.    By  A.  A.  Houghton. 

A  number  of  designs  with  working  drawings  of  molds  are  fully  explained  so  anyone 
can  easily  construct  different  styles  of  ornamental  concrete  porches  without  the  pur- 
chase of  expensive  molds.     (No.  9  of  Series.) 75  cents 

MOLDING    CONCRETE   FLOWER-POTS,   BOXES,   JARDINIERES,   ETC. 

By  A.  A.  Houghton. 

The  molds  for  producing  many  original  designs  of  flower-pots,  urns,  flower-boxes, 
jardinieres,  etc.,  are  fully  illustrated  and  explained,  so  the  worker  can  easily  construct 
and  operate  same.     (No.  10  of  Series.) 75   cents 

MOLDING  CONCRETE  FOUNTAINS  AND  LAWN  ORNAMENTS.    By  A. 
A.  Houghton. 

The  molding  of  a  number  of  designs  of  lawn  seats,  curbing,  hitching  posts,  pergolas,  sun 
dials  and  other  forms  of  ornamental  concrete  for  the  ornamentation  of  lawns  and  gar- 
dens, is  fully  illustrated  and  described.     (No.  11  of  Series) 75   cents 

CONCRETE  FROM  SAND  MOLDS.    By  A.  A.  Houghton. 

A  Practical  Work  treating  on  a  process  which  has  heretofore  been  held  as  a  trade  secret 
by  the  few  who  possessed  it,  and  which  will  successfully  mold  every  and  any  class  of 
ornamental  concrete  work.  The  process  of  molding  concrete  with  sand  molds  is  of 
the  utmost  practical  value,  possessing  the  manifold  advantages  of  a  low  cost  of  molds, 
the  ease  and  rapidity  of  operation,  perfect  details  to  all  ornamental  designs,  density 
and  increased  strength  of  the  concrete,  perfect  curing  of  the  work  without  attention 
and  the  easy  removal  of  the  molds  regardless  of  any  undercutting  the  design  may  have. 
192  pages.     Fully  illustrated.    Price $3.00 

ORNAMENTAL    CONCRETE    WITHOUT    MOLDS.     By  A.  A.  Houghton. 

The  process  for  making  ornamental  concrete  without  molds  has  long  been  held  as  a 
secret,  and  now,  for  the  first  time,  this  process  is  given  to  the  public.  The  book 
reveals  the  secret  and  is  the  only  book  published  which  explains  a  simple,  practical 
method  whereby  the  concrete  worker  is  enabled,  by  employing  wood  and  metal  tem- 
plates of  different  designs,  to  mold  or  model  in  concrete  any  Cornice,  Archivolt, 
Column,  Pedestal,  Base  Cap,  Urn  or  Pier  in  a  monolithic  form — right  upon  the  job. 
These  may  be  molded  in  units  or  blocks,  and  then  built  up  to  suit  the  specifications 
demanded.     This  work  is  fully  illustrated,  with  detailed  engravings.     Price  .     $2.00 

CONCRETE   FOR    THE    FARM    AND    IN   THE    SHOP.     By    H.   Colin 
Campbell,  C.E.,  E.M. 

A  new  book  illustrating  and  describing  in  plain,  simple  language  many  of  the 
numerous  applications  of  concrete  within.the  range  of  the  home  worker.  Among  the 
subjects  treated  are: 

Principles  of  reinforcing ;  methods  of  protecting  concrete  so  as  to  insure  proper  harden- 
ing; home-made  mixers;  mixing  by  hand  and  machine;  form  construction,  described 
and  illustrated  by  drawings  and  photographs;  construction  of  concrete  walls  and 
fences;  concrete  fence  posts;  concrete  gate  posts;  corner  posts;  clothes  line  posts; 
grape  arbor  posts;  tanks;  troughs;  cisterns;  hog  wallows;  feeding  floors  and  barn- 
yard pavements ;  foundations ;  well  curbs  and  platforms ;  indoor  floors ;  sidewalks ;  steps ; 
concrete  hotbeds  and  cold  frames ;  concrete  slab  roofs ;  walls  for  buildings ;  repairing 
leaks  in  tanks  and  cisterns,  etc.,  etc.  A  number  of  convenient  and  practical  tables 
for  estimating  quantities,  and  some  practical  examples,  are  also  given.  (5  x  7). 
149  pages,  51  illustrations.    Price $1.00 

II 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 

POPULAR   HANDBOOK   FOR   CEMENT  AND   CONCRETE   USERS.    By 

Myron  H.  Lewis. 

This  is  a  concise  treatise  of  the  principles  and  methods  employed  in  the  manufacture 
and  use  of  cement  in  all  classes  of  modern  works.  The  author  has  brought  together 
in  this  work  all  the  salient  matter  of  interest  to  the  user  of  concrete  and  its  many 
diversified  products.  The  matter  is  presented  in  logical  and  systematic  order,  clearly 
written,  fully  illustrated  and  free  from  involved  mathematics.  Everything  of  value  to 
the  concrete  user  is  given,  including  kinds  of  cement  employed  in  construction,  concrete 
architecture,  inspection  and  testing,  waterproofing,  coloring  and  painting,  rules,  tables, 
working  and  cost  data.  The  book  comprises  thirty-three  chapters,  430  pages,  126 
illustrations.      Price $3.00 

WATERPROOFING  CONCRETE.    By  Myron  H.  Lewis. 

Modern  Methods  of  Waterproofing  Concrete  and  Other  Structures.  A  condensed 
statement  of  the  Principles,  Rules,  and  Precautions  to  be  Observed  in  Waterproofing 
and  Dampproofing  Structures  and  Structural  Materials.    Price    ....     75  cents 

DICTIONARIES 

STANDARD  ELECTRICAL  DICTIONARY.    By  T.  O'Conor  Sloane. 

An  indispensable  work  to  all  interested  in  electrical  science.  Suitable  alike  for  the 
student  and  professional.  A  practical  handbook  of  reference  containing  definitions  in 
about  5000  distinct  words,  terms  and  phrases.  The  definitions  are  terse  and  concise 
and  include  every  term  used  in  electrical  science.  Recently  issued.  An  entirely  new 
edition.  Should  be  in  the  possession  of  all  who  desire  to  keep  abreast  with  the  progress 
of  this  branch  of  science.  Complete,  concise  and  convenient.  Nearly  800  pages.  Nearly 
500  illustrations.     New  Revised  and  Enlarged  Edition.     Price $5.00 

DIES— METAL  WORK 

DIES:  THEIR  CONSTRUCTION  AND  USE  FOR  THE  MODERN  WORKING 
OF  SHEET  METALS.     By  J.  V.  Woodworth. 

A  most  useful  book,  and  one  which  should  be  in  the  hands  of  all  engaged  in  the  pres- 
working  of  metals ;  treating  on  the  Designing,  Constructing,  and  Use  of  Tools,  Fixtures 
and  Devices,  together  with  the  manner  in  which  they  should  be  used  in  the  Power 
Press,  for  the  cheap  and  rapid  production  of  the  great  variety  of  sheet-metal  articles 
now  in  use.  It  is  designed  as  a  guide  to  the  production  of  sheet-metal  parts  at  the 
minimum  of  cost  with  the  maximum  of  output.  The  hardening  and  tempering  of 
Press  tools  and  the  classes  of  work  which  may  be  produced  to  the  best  advantage  by 
the  use  of  dies  in  the  power  press  are  fully  treated.  Its  505  illustrations  show  dies, 
press  fixtures  and  sheet-metal  working  devices,  the  descriptions  of  which  are  so  clear  and 
practical  that  all  metal-working  mechanics  will  be  able  to  understand  how  to  design, 
construct  and  use  them.  Many  of  the  dies  and  press  fixtures  treated  were  either 
constructed  by  the  author  or  under  his  supervision.  Others  were  built  by  skilful 
mechanics  and  are  in  use  in  large  sheet-metal  establishments  and  machine  shops. 
6th  Edition.     400  pages,  523  illustrations.     Price $3.50 

PUNCHES,  DIES  AND  TOOLS  FOR  MANUFACTURING  IN  PRESSES.    By 

J.  V.  Woodworth. 

This  work  is  a  companion  volume  to  the  author's  elementary  work  entitled  "Dies,  Their 
Construction  and  Use."  It  does  not  go  into  the  details  of  die-making  to  the  extent  of 
the  author's  previous  book,  but  gives  a  comprehensive  review  of  the  field  of  operations 
carried  on  by  presses.  A  large  part  of  the  information  given  has  been  drawn  from  the 
author's  personal  experience.  It  might  well  be  termed  an  Encyclopedia  of  Die-Making, 
Punch-Making,  Die-Sinking,  Sheet-Metal  Working,  and  Making  of  Special  Tools,  Sub- 

{wesses,  Devices  and  Mechanical  Combinations  for  Punching,  Cutting,  Bending,  Form- 
ng,  Piercing,  Drawing,  Compressing  and  Assembling  Sheet-Metal  Parts,  and  also  Arti- 
cles of  other  Materials  in  Machine  Tools.  3rd  Edition.  483  pages,  702  illustrations. 
Price $4.50 

I? 


CATALOGUE  OF  GOoO,  PRACTICAL  BOOKS 


DRAWING— SKETCHING  PAPER 

PRACTICAL  PERSPECTIVE.     By  Richards  and  Colvin. 

Shows  just  how  to  make  all  kinds  of  mechanical  drawings  in  the  only  practical  per- 
spective isometric.  Makes  everything  plain  so  that  any  mechanic  can  understand 
a  sketch  or  drawing  in  this  way.  Saves  time  in  the  drawing  room,  and  mistakes  in  the 
shops.  Contains  practical  examples  of  various  classes  of  work.  4th  Edition.    75  cents 

LINEAR  PERSPECTIVE  SELF-TAUGHT.    By  Herman  T.  C.  Kraus. 

This  work  gives  the  theory  and  practice  of  linear  perspective,  as  used  in  architectural, 
engineering  and  mechanical  drawings.  Persons  taking  up  the  study  of  the  subject 
by  themselves  will  be  able,  by  the  use  of  the  instruction  given,  to  readily  grasp  the 
subject,  and  by  reasonable  practice  become  good  perspective  draftsmen.  The  arrange- 
ment of  the  book  is  good;  the  plate  is  on  the  left-hand,  while  the  descriptive  text 
follows  on  the  opposite  page,  so  as  to  be  readily  referred  to.  The  drawings  are  on 
sufficiently  large  scale  to  show  the  work  clearly  and  are  plainly  figured.  There  is 
included  a  self-explanatory  chart  which  gives  all  information  necessary  for  the  thorough 
understanding  of  perspective.  This  chart  alone  is  worth  many  times  over  the  price  of 
the  book.    2d  Revised  and  enlarged  Edition $3.00 

SELF-TAUGHT  MECHANICAL  DRAWING  AND  ELEMENTARY  MACHINE 
DESIGN.  By  F.  L.  Sylvester,  M.E.,  Draftsman,  with  additions  by  Erik 
Oberg,  associate  editor  of  "Machinery." 

This  is  a  practical  treatise  on  Mechanical  Drawing  and  Machine  Design,  comprising 
the  first  principles  of  geometric  and  mechanical  drawing,  workshop  mathematics, 
mechanics,  strength  of  materials  and  the  calculations  and  design  of  machine  details. 
The  author's  aim  has  been  to  adapt  this  treatise  to  the  requirements  of  the  practical 
mechanic  and  young  draf tsman  and  to  present  the  matter  in  as  clear  and  concise  a 
manner  as  possible.  To  meet  the  demands  of  this  class  of  students,  practically  all  the 
important  elements  of  machine  design  have  been  dealt  with,  and  in  addition  algebraic 
formulas  have  been  explained,  and  the  elements  of  trigonometry  treated  in  the  manner 
best  suited  to  the  needs  of  the  practical  man.  The  book  is  divided  into  20  chapters, 
and  in  arranging  the  material,  mechanical  drawing,  pure  and  simple,  has  been  taken 
up  first,  as  a  thorough  understanding  of  the  principles  of  representing  objects  facilitates 
the  further  study  of  mechanical  subjects.  This  is  followed  by  the  mathematics  neces- 
sary for  the  solution  of  the  problems  in  machine  design  which  are  presented  later,  and 
a  practical  introduction  to  theoretical  mechanics  and  the  strength  of  materials.  The 
various  elements  entering  into  machine  design,  such  as  cams,  gears,  sprocket-wheels, 
cone  pulleys,  bolts,  screws,  couplings,  clutches,  shafting  and  fly-wheels,  have  been 
treated  in  such  a  way  as  to  make  possible  the  use  of  the  work  as  a  text-book  for  a 
continuous  course  of  study.         333  pages,  218  engravings.     Price.     .     .     .     $2.50 

A  NEW  SKETCHING  PAPER. 

A  new  specially  ruled  paper  to  enable  you  to  make  sketches  or  drawings  in  isometric 
perspective  without  any  figuring  or  fussing.  It  is  being  used  for  shop  details  as  well 
as  for  assembly  drawings,  as  it  makes  one  sketch  do  the  work  of  three,  and  no  workman 
can  help  seeing  just  what  is  wanted.  Pads  of  40  sheets,  6x9  inches,  40  cents.  Pads 
of  40  sheets,  9x12  inches,  75  cents;  40  sheets,  12x18,  Price $1.50 

ELECTRICITY 


ARITHMETIC  OF  ELECTRICITY.    By  Prof.  T.  O'Conor  Sloane. 

A  practical  treatise  on  electrical  calculations  of  all  kinds  reduced  to  a  series  of  rules,  all 
of  the  simplest  forms,  and  involving  only  ordinary  arithmetic;  each  rule  illustrated 
by  one  or  more  practical  problems,  with  detailed  solution  of  each  one.  This  book  is 
classed  among  the  most  useful  works  published  on  the  science  of  electricity,  covering 
as  it  does  the  mathematics  of  electricity  in  a  manner  that  will  attract  the  attention 
of  those  who  are  not  familiar  with  algebraical  formulas.  22nd  Edition.  196  pages. 
Price $1.50 

13 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 

COMMUTATOR  CONSTRUCTION.    By  Wm.  Baxter,  Jr. 

The  business  end  of  any  dynamo  or  motor  of  the  direct  current  type  is  the  commutator. 
This  book  goes  into  the  designing,  building,  and  maintenance  of  commutators,  shows 
how  to  locate  troubles  and  how  to  remedy  them;  everyone  who  fusses  with  dynamos 
needs  this.    5th  Edition   . .35  cents 

CONSTRUCTION  OF  A  TRANSATLANTIC  WIRELESS  RECEIVING  SET. 

By  L.  G.  Pacent  and  T.  S.  Curtis. 

A  work  for  the  Radio  student  who  desires  to  construct  and  operate  apparatus  that 
will  permit  of  the  reception  of  messages  from  the  large  stations  in  Europe  with  an 
aerial  of  amateur  proportions.     36  pages.     23  illustrations,  cloth.     Price  .  35  cents 

DYNAMO  BUILDING  FOR  AMATEURS,  OR  HOW  TO  CONSTRUCT  A 
FIFTY- WATT  DYNAMO.  By  Arthur  J.  Weed,  Member  of  N.  Y.  Electrical 
Society. 

A  practical  treatise  showing  in  detail  the  construction  of  a  small  dynamo  or  motor,  the 
entire  machine  work  of  which  can  be  done  on  a  small  foot  lathe.  Dimensioned  working 
drawings  are  given  for  each  piece  of  machine  work,  and  each  operation  is  clearly 
described.  This  machine,  when  used  as  a  dynamo,  has  an  output  of  fifty  watts;  when 
used  as  a  motor  it  will  drive  a  small  drill  press  or  lathe.  It  can  be  used  to  drive  a 
sewing  machine  on  any  and  all  ordinary  work.  The  book  is  illustrated  with  more 
than  sixty  original  engravings  showing  the  actual  construction  of  the  different  parts. 
Among  the  contents  are  chapters  on:  1.  Fifty-Watt  Dynamo.  2.  Side  Bearing 
Rods.  3.  Field  Punching.  4.  Bearings.  5.  Commutator.  6.  Pulley..  7.  Brush 
Holders.  8.  Connection  Board.  9.  Armature  Shaft.  10.  Armature.  11.  Armature 
Winding.      12.  Field  Winding.     13.  Connecting  and  Starting.      Price,  cloth,     $1.00 

DESIGN   DATA   FOR   RADIO   TRANSMITTERS   AND    RECEIVERS.    By 

Milton  B.  Sleeper. 

Far  from  being  a  collection  of  formulas,  Design  Data  takes  up  in  proper  sequence  the 
problems  encountered  in  planning  all  types  of  receiving  sets  for  short,  medium  and 
long  wave  work,  and  spark  coil,  transformer  and  vacuum  tube  transmitters  operating 
on  200  meters.  Tables  have  been  worked  out  so  that  values  can  be  found  without 
the  use  of  mathematics.  Radio  experimenters  will  find  here  information  which  will 
enable  them  to  have  the  most  modern  and  efficient  equipment.     Price  .      .     75  cents 

DYNAMOS   AND   ELECTRIC   MOTORS   AND   ALL   ABOUT   THEM.     By 

Edward  Trevert. 

This  volume  gives  practical  directions  for  building  a  two  H.  P.  Dynamo  of  the  Edison 
type  capable  of  lighting  about  fifty  mazda  lamps  of  the  20-watt  size.  In  addition,  it 
gives  directions  for  building  two  small  electric  motors  suitable  for  running  sewing 
machines.  The  concluding  chapter  describes  the  construction  of  a  simple  bichromate 
battery  adapted  for  running  electric  motors.  96  pages.  Fully  illustrated  with  detail 
drawings.     Cloth.     Price $1.00 

ELECTRIC  BELLS.     By  M.-  B.  Sleeper. 

A  complete  treatise  for  the  practical  worker  in  installing,  operating,  and  testing 
bell  circuits,  burglar  alarms,  thermostats,  and  other  apparatus  used  with  electric 
bells.  Both  the  electrician  and  the  experimenter  will  find  in  this  book  new  material 
which  is  essential  in  their  work.  Tools,  bells,  batteries,  unusual  circuits,  burglar 
alarms,  annunciators,  systems,  thermostats,  circuit  breakers,  time  alarms,  and  other 
apparatus  used  in  bell  circuits  are  described  from  the  standpoints  of  their  applica- 
tion, construction,  and  repair.  The  detailed  instructions  for  building  the  apparatus 
will  appeal  to  the  experimenter  particularly.  The  practical  worker  will  find  the 
chapters  on  Wiring  Calculation  of  Wire  Sizes  and  Magnet  Windings,  Upkeep  of 
Systems  and  the  Location  of  Faults  of  the  greatest  value  in  their  work.  124  pages. 
Fully  illustrated.     Price 75  cents 

14 


CATALOGUE   OF  GOOD,  PRACTICAL  BOOKS 

EXPERIMENTAL   HIGH  FREQUENCY  APPARATUS  —  HOW  TO   MAKE 

AND  USE  IT.     By  Thomas  Stanley  Curtis. 

This  book  tells  you  how  to  build  simple  high  frequency  coils  for  experimental  purpose 
in  the  home,  school  laboratory,  or  on  the  small  lecture  platform.  The  book  is  really 
a  supplement  to  the  same  author's  "High  Frequency  Apparatus."  The  experimental 
side  only  is  covered  in  this  volume,  which  is  intended  for  those  who  want  to  build 
small  coils  giving  up  to  an  eighteen-inch  spark.  The  book  contains  valuable  in- 
formation for  the  physics  or  the  manual  training  teacher  who  is  on  the  lookout  for 
interesting  projects  for  his  boys  to  build  or  experiment  with.  The  apparatus  is 
simple,  cheap  and  perfectly  safe,  and  with  it  some  truly  startling  experiments  may  be 
performed.  Among  the  contents  are:  Induction  Con  Outfits  Operated  on  Battery 
Current.  Kicking  Coil  Apparatus.  One-Half  Kilowatt  Transformer  Outfit.  Parts 
and  Materials,  etc.,  etc.     69  pages.     Illustrated.     Price 50  cents 

HIGH  FREQUENCY  APPARATUS,  ITS  CONSTRUCTION  AND  PRACTICAL 
APPLICATION.     By  Thomas  Stanley  Curtis. 

The  most  comprehensive  and  thorough  work  on  this  interesting  subject  ever  produced. 
The  book  is  essentially  practical  in  its  treatment  and  it  constitutes  an  accurate  record 
of  the  researches  of  its  author  over  a  period  of  several  years,  during  which  time  dozens 
of  coils  were  built  and  experimented  with.  The  work  has  been  divided  into  six  basic 
parts.  The  first  two  chapters  tell  the  uninitiated  reader  what  the  high  frequency 
current  is,  what  it  is  used  for,  and  how  it  is  produced.  The  second  section,  comprising 
four  chapters,  describes  in  detail  the  principles  of  the  transformer,  condenser,  spark 
gap,  and  oscillation  transformer,  and  covers  the  main  points  in  the  design  and  con- 
struction of  these  devices  as  applied  to  the  work  in  hand.  The  third  section  covers 
the  construction  of  small  high  frequency  outfits  designed  for  experimental  work  in  the 
home  laboratory  or  in  the  classroom.  The  fourth  section  is  devoted  to  electro- 
therapeutic  and  X-Ray  apparatus.  The  fifth  describes  apparatus  for  the  cultivation 
of  plants  and  vegetables.  The  sixth  section  is  devoted  to  a  comprehensive  discussion 
of  apparatus  of  large  size  for  use  upon  the  stage  in  spectacular  productions.  The 
closing  chapter,  giving  the  current  prices  of  the  parts  and  materials  required  for  the 
construction  of  the  apparatus  described,  is  included  with  a  view  to  expediting  the 
purchase  of  the  necessary  goods.  The  Second  Edition  includes  much  new  matter 
along  the  line  of  home-made  therapeutic  outfits  for  physicians'  use.  The  matter  on 
electro  plant  culture  has  also  been  elaborated  upon.  Second  Revised  and  Enlarged 
Edition.     266  pages.     New  second  edition.     Fully  illustrated.     Price       .     $3.00 

ELECTRIC   WIRING,    DIAGRAMS  AND    SWITCHBOARDS.    By  Newton 
Harrison. 

A  thoroughly  practical  treatise  covering  the  subject  of  Electric  Wiring  in  all  its  branches, 
including  explanations  and  diagrams  which  are  thoroughly  explicit  and  greatly  simplify 
the  subject.  Practical,  every-day  problems  in  wiring  are  presented  and  the  method 
of  obtaining  intelligent  results  clearly  shown.  Only  arithmetic  is  used.  Ohm's  law 
is  given  a  simple  explanation  with  reference  to  wiring  for  direct  and  alternating 
currents.  The  fundamental  principle  of  drop  of  potential  in  circuits  is  shown  with  its 
various  applications.  The  simple  circuit  is  developed  with  the  position  of  mains, 
feeders  and  branches;  their  treatment  as  a  part  of  a  wiring  plan  and  their  employ- 
ment in  house  wiring  clearly  illustrated.  Some  simple  facts  about  testing  are  included 
in  connection  with  the  wiring.  Molding  and  conduit  work  are  given  careful  considera- 
tion; and  switchboards  are  systematically  treated,  built  up  and  illustrated,  showing 
the  purpose  they  serve,  for  connection  with  the  circuits,  and  to  shunt  and  compound 
wound  machines.  The  simple  principles  of  switchboard  construction,  the  develop- 
ment of  the  switchboard,  the  connections  of  the  various  instruments,  including  the 
lightning  arrester,  are  also  plainly  set  forth. 

Alternating  current  wiring  is  treated,  with  explanations  of  the  power  factor,  conditions 
calling  for  various  sizes  of  wire,  and  a  simple  way  of  obtaining  the  sizes  for  single-phase, 
two-phase  and  three-phase  circuits.  This  is  the  only  complete  work  issued  showing 
and  telling  you  what  you  should  know  about  direct  and  alternating  current  wiring.  It 
is  a  ready  reference.  The  work  is  free  from  advanced  technicalities  and  mathematics, 
arithmetic  being  used  throughout.  It  is  in  every  respect  a  handy,  well-written, 
instructive,  comprehensive  volume  on  wiring  for  the  wireman,  foreman,  contractor, 
or  electrician.  3rd  edition,  revised  and  enlarged.  315  pages;  137  illustrations. 
Price $2.50 

IS 


CATALOGUE   OF  GOOD,  PRACTICAL  BOOKS 

ELECTRIC  TOY  MAKING,  DYNAMO  BUILDING,  AND  ELECTRIC  MOTOR 
CONSTRUCTION.    By  Prof.  T.  O'Conor  Sloane. 

This  work  treats  of  the  making  at  home  of  electrical  toys,  electrical  apparatus,  motors, 
dynamos  and  instruments  in  general,  and  is  designed  to  bring  within  the  reach  of 
young  and  old  the  manufacture  of  genuine  and  useful  electrical  appliances.  The  work 
is  especially  designed  for  amateurs  and  young  folks. 

Thousands  of  our  young  people  are  daily  experimenting,  and  busily  engaged  in  making 
electrical  toys  and  apparatus  of  various  kinds.  The  present  work  is  just  what  is  want- 
ed to  give  the  much  needed  information  in  a  plain,  practical  manner,  with  illustrations 
to  make  easy  the  carrying  out  of  the  work.  20th  Edition.  210  pages,  77  illustrations. 
Price $1.50 

ELECTRICIANS*  HANDY  BOOK.     By  Prof.  T.  O'Conor  Sloane. 

This  work  is  intended  for  the  practical  electrician  who  has  to  make  things  go.  The 
entire  field  of  electricity  is  covered  within  its  pages.  Among  some  of  the  subjects  treated 
are:  The  Theory  of  the  Electric  Current  and  Circuit,  Electro-Chemistry,  Primary 
Batteries,  Storage  Batteries,  Generation  and  Utilization  of  Electric  Powers,  Alter- 
nating Current,  Armature  Winding,  Dynamos  and  Motors,  Motor  Generators, 
Operation  of  the  Central  Station  Switchboards,  Safety  Appliances,  Distribution 
of  Electric  Light  and  Power,  Street  Mains,  Transformers,  Arc  and  Incandescent 
Lighting,  Electric  Measurements,  Photometry,  Electric  Railways,  Telephony,  Bell- 
Wiring,  Electric-Plating,  Electric  Heating,  Wireless  Telegraphy,  etc.  It  contains  no 
useless  theory;  everything  is  to  the  point.  It  teaches  you  just  what  you  want  to 
know  about  electricity.  It  is  the  standard  work  published  on  the  subject.  Forty- 
six  chapters,  600  engravings.     New  5th  Edition,  Revised  and  Enlarged.     Price   $4.00 

ELECTRICITY  SIMPLIFIED.     By  Prof.  T.  Q'Conor  Sloane. 

The  object  of  "Electricity  Simplified"  is  to  make  the  subject  as  plain  as  possible  and 
to  show  what  the  modern  conception  of  electricity  is;  to  show  how  two  plates  of 
different  metal,  immersed  in  acid,  can  send  a  message  around  the  globe;  to  explain 
how  a  bundle  of  copper  wire  rotated  by  a  steam  engine  can  be  the  agent  in  lighting 
our  streets,  to  tell  what  the  volt,  ohm  and  ampere  are,  and  what  high  and  low  tension 
mean;  and  to  answer  the  questions  that  perpetually  arise  in  the  mind  in  this  age  of 
electricity.     15th  Revised  Edition.     218  pages.     Illustrated.     Price     .      .     $1.50 

EXPERIMENTAL  WIRELESS  STATIONS.     By  P.  E.  Edelman. 

The  theory,  design,  construction  and  operation  is  fully  treated  including  Wireless 
Telephony,  Vacuum  Tube,  and  quenched  spark  systems.  The  new  enlarged  edition 
is  just  issued  and  is  strictly  up  to  date,  correct  and  complete.  This  book  tells 
how  to  make  apparatus  to  not  only  hear  all  telephoned  and  telegraphed  radio  mes- 
sages, but  also  how  to  make  simple  equipment  that  works  for  transmission  over  rea- 
sonably long  distances.  Then  there  is  a  host  of  new  information  included.  The 
first  and  only  book  to  give  you  all  the  recent  important  radio  improvements,  some 
of  which  have  never  before  been  published.  This  volume  anticipates  every  need  of 
the  reader  who  wants  the  gist  of  the  art,  its  principles,  simplified  calculations,  appara- 
tus dimensions,  and  understandable  directions  for  efficient  operation. 
Vacuum  tube  circuits;  amplifiers;  long-distance  sets;  loop,  coil,  and  underground 
receivers;  tables  of  wave-lengths,  capacity,  inductance;  such  are  a  few  of  the  sub- 
jects presented  in  detail  that  satisfies.  It  is  independent  and  one  of  the  few  that 
describe  all  modern  systems. 

Endorsed  by  foremost  instructors  for  its  clear  accuracy,  preferred  by  leading  amateurs 
for  its  dependable  designs.  The  new  experimental  Wireless  Stations  is  sure 
to  be  most  satisfactory  for  your  purposes.  27  chapters,  392  pages.  167  illustra- 
tions.    Price         $3.00 

RADIO  TIME  SIGNAL  RECEIVER.     By  Austin  C.  Lescarboura. 

This  new  book,  "A  Radio  Time  Signal  Receiver,"  tells  you  how  to  build  a  simple 
outfit  designed  expressly  for  the  beginner.  You  can  build  the  outfits  in  your  own 
workshop  and  install  them  for  jewelers  either  on  a  one-payment  or  a  rental  basis. 
The  apparatus  is  of  such  simple  design  that  it  may  be  made  by  the  average  amateur 
mechanic  possessing  a  few  ordinary  tools.     42  pages.     Paper.     Price     .      .    35  cents 

16 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 

HOUSE  WIRING.     By  Thomas  W.  Poppe. 

This  work  describes  and  illustrates  the  actual  installation  of  Electric  Light  Wiring, 
the  manner  in  which  the  work  should  he  done,  and  the  method  of  doing  it.  The  book 
can  be  conveniently  carried  in  the  pocket.  It  is  intended  for  the  Electrician,  Helps, 
and  Apprentice.  It  solves  all  Wiring  Problems  and  contains  nothing  that  conflicts 
with  the  rulings  of  the  National  Board  of  Fire  Underwriters.  It  gives  just  the  informa- 
tion essential  to  the  Successful  Wiring  of  a  Building.  Among  the  subjects  treated  are 
Locating  the  Meter.  Panel  Boards.  Switches.  Plug  Receptacles.  Brackets.  Ceiling 
Fixtures.  The  Meter  Connections.  The  Feed  Wires.  The  Steel  Armored  Cable 
System.  The  Flexible  Steel  Conduit  System.  The  Ridig  Conduit  System.  A  digest 
of  the  National  Board  of  Fire  Underwriters'  rules  relating  to  metallic  wiring  systems. 
Various  switching  arrangements  explained  and  diagrammed.  The  easiest  method  or 
testing  the  Three-  and  Four- way  circuits  explained.  The  grounding  of  all  metallic 
wiring  systems  and  the  reason  for  doing  so  shown  and  explained.  The  insulation  of 
the  metal  parts  of  lamp  fixtures  and  the  reason  for  the  same  described  and  illustrated. 
208  pages.  4th  Edition,  revised  and  enlarged.  160  illustrations.  Flexible  cloth. 
Price $1.00 

HOW  TO  BECOME  A  SUCCESSFUL  ELECTRICIAN.    By  Prof.  T.  0'Conor 
Sloane. 

Every  young  man  who  wishes  to  become  a  successful  electrician  should  read  this  book. 
It  tells  in  simple  language  the  surest  and  easiest  way  to  become  a  successful  electrician. 
The  studies  to  be  followed,  methods  of  work,  field  of  operation  and  the  requirement, 
of  the  successful  electrician  are  pointed  out  and  fully  explained.  Every  young  en- 
gineer will  find  this  an  excellent  stepping  stone  to  more  advanced  works  on  electricity 
which  he  must  master  before  success  can  be  attained.  Many  young  men  become  dis- 
couraged at  the  very  outstart  by  attempting  to  read  and  study  books  that  are  far 
beyond  their  comprehension.  This  book  serves  as  the  connecting  link  between  the 
rudiments  taught  in  the  public  schools  and  the  real  study  of  electricity.  It  is  inter- 
esting from  cover  to  cover.  19th  Revised  Edition,  just  issued.  205  pages.  Illus- 
trated.   Price $1.50 

RADIO  HOOK-UPS.     By  Milton  B.  Sleeper. 

In  this  book  the  best  circuits  for  different  instruments  and  various  purposes  have  been 
carefully  selected  and  grouped  together.  All  the  best  circuits  for  damped  and  un- 
damped wave  receiving  sets,  buzzer,§spark  coil  and  transformer  sending  equipment,  as 
well  as  vacuum  tube  telegraph  and  telephone  transmitters,  wavemeters,  vacuum  tube 
measuring  instruments,  audibility  meters,  etc.,  are  shown  in  this  book.   .     75  cents 

STANDARD  ELECTRICAL  DICTIONARY.    By  T.  O'Ccnor  Sloane. 

An  indispensable  work  to  all  interested  in  electrical  science.  Suitable  alike  for  the 
student  and  professional.  A  practical  handbook  of  reference  containing  definitions 
of  about  5,000  distinct  words,  terms  and  phrases.  The  definitions  are  terse  and 
concise  and  include  every  term  used  in  electrical  science.  Recently  issued.  An  en- 
tirely new  edition.  Should  be  in  the  possession  of  all  who  desire  to  keep  abreast  with 
the  progress  of  this  branch  of  science.  In  its  arrangement  and  typography  the  book 
is  very  convenient.  The  word  or  term  defined  is  printed  in  black-faced  type  which 
readily  catches  the  eye,  while  the  body  of  the  page  is  in  smaller  but  distinct  type.  The 
definitions  are  well  worded,  and  so  as  to  be  understood  by  the  non-technical  reader. 
The  general  plan  seems  to  be  to  give  an  exact,  concise  definition,  and  then  amplify 
and  explain  in  a  more  popular  way.  Synonyms  are  also  given,  and  references  to  other 
words  and  phrases  are  made.  A  very  complete  and  accurate  index  of  fifty  pages  is 
at  the  end  of  the  volume ;  and  as  this  index  contains  all  synonyms,  and  as  all  phrases 
are  indexed  in  every  reasonable  combination  of  words,  reference  to  the  proper  place 
in  the  body  of  the  book  is  readily  made.  It  is  difficult  to  decide  how  far  a  book  of 
this  character  is  to  keep  the  dictionary  form,  and  to  what  extent  it  may  assume  the 
encyclopedia  form.  For  some  purposes,  concise,  exactly  worded  definitions  are  needed ; 
for  other  purposes,  more  extended  descriptions  are  required.  This  book  seeks  to  satisfy 
both  demands,  and  does  it  with  considerable  success.  Complete,  concise  and  con- 
venient. 800  pages.  Nearly  500  illustrations.  New  Revised  and  Enlarged  Edition. 
Price .     ,    ,        .    , $5.00 

J7 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 

^1  I  H ■■■III!        ■M^MIIIIIII    I    M       _|. „_ ■IWIBW     ■■■!  Illll     III1IIIIW     ■■  I    ■  I  "^"^^ 

STORAGE  BATTERIES  SIMPLIFIED.    By  Victor  W.  Page,  M.S.A.E. 

A  complete  treatise  on  storage  battery  operating  principles,  repairs  and  applications. 
The  greatly  increasing  application  of  storage  batteries  in  modern  engineering  and 
mechanical  work  has  created  a  demand  for  a  book  that  will  consider  this  subject 
completely  and  exclusively.  This  is  the  most  thorough  and  authoritative  treatise 
ever  published  on  this  subject.  It  is  written  in  easily  understandable,  non-technical 
language  so  that  anyone  may  grasp  the  basic  principles  of  storage  battery  action  as 
well  as  their  practical  industrial  applications.  All  electric  and  gasoline  automobiles 
use  storage  batteries.  Every  automobile  repairman,  dealer  or  salesman  should  have  a 
good  knowledge  of  maintenance  and  repair  of  these  important  elements  of  the  motor 
car  mechanism.  This  book  not  only  tells  how  to  charge,  care  for  and  rebuild  storage 
batteries  but  also  outlines  all  the  industrial  uses.  Learn  how  they,  run  street  cars, 
locomotives  and  factory  trucks.  Get  an  understanding  of  the  important  functions  they 
perform  in  submarine  boats,  isolated  lighting  plants,  railway  switch  and  signal  systems, 
marine  applications,  etc.  This  book  tells  how  they  are  used  in  central  station  standby 
service,  for  starting  automobile  motors  and  in  ignition  systems.  Every  practical  use 
of  the  modern  storage  battery  is  outlined  in  this  treatise.  208  pages.  Fully  illus- 
trated.   Price $2.00 

TELEPHONE  CONSTRUCTION,  INSTALLATION,  WIRING,  OPERATION 
AND  MAINTENANCE.    By  W.  H.  Radcliffe  and  H.  G.  Cushinq. 

This  book  is  intended  for  the  amateur,  the  wireman,  or  the  engineer  who  desires  to 
establish  a  means  of  telephonic  communication  between  the  rooms  of  his  home,  office, 
or  shop.  It  deals  only  with  such  things  as  may  be  of  use  to  him  rather  than  with 
theories. 

Gives  the  principles  of  construction  and  operation  of  both  the  Bell  and  Independent* 
instruments;  approved  methods  of  installing  and  wiring  them;  the  means  of  protecting 
them  from  lightning  and  abnormal  currents;  their  connection  together  for  operation 
as  series  or  bridging  stations ;  and  rules  for  their  inspection  and  maintenance.  Line 
wiring  and  the  wiring  and  operation  of  special  telephone  systems  are  also  treated. 
Intricate  mathematics  are  avoided,  and  all  apparatus,  circuits  and  systems  are  thor- 
oughly described.  The  appendix  contains  definitions  of  units  and  terms  used  in  the 
text.  Selected  wiring  tables,  which  are  very  helpful,  are  also  included.  Among  the 
subjects  treated  are  Construction,  Operation,  and  Installation  of  Telephone  Instru- 
ments; Inspection  and  Maintenance  of  Telephone  Instruments;  Telephone  Line 
Wiring;  Testing  Telephone  Line  Wires  and  Cables ;  Wiring  and  Operation  of  Special 
Telephone  Systems,  etc.  2nd  Edition,  revised  and  enlarged.  223  pages.  154 
illustrations $1.50 

WIRELESS  TELEGRAPHY  AND  TELEPHONY  SIMPLY  EXPLAINED.    By 
Alfred  P.  Morgan. 

This  is  undoubtedly  one  of  the  most  complete  and  comprehensible  treatises  on  the 
subject  ever  published,  and  a  close  study  of  its  pages  will  enable  one  to  master  all  the 
details  of  the  wireless  transmission  of  messages.  The  author  has  filled  a  long-felt 
want  and  has  succeeded  in  furnishing  a  lucid,  comprehensible  explanation  in  simple 
language  of  the  theory  and  practice  of  wireless  telegraphy  and  telephony. 
Among  the  contents  are:  Introductory;  Wireless  Transmission  and  Reception — The 
Aerial  System,  Earth  Connections — The  Transmitting  Apparatus,  Spark  Coils  and 
Transformers,  Condensers,  Helixes,  Spark  Gaps,  Anchor  Gaps,  Aerial  Switches — The 
Receiving  Apparatus.  Detectors,  etc. — Tuning  and  Coupling,  Tuning  Coils,  Loose 
Couplers,  Variable  Condensers,  Directive  Wave  Systems — Miscellaneous  Apparatus, 
Telephone  Receivers,  Range  of  Stations,  Static  Interference — Wireless  Telephones, 
Sound  and  Sound  Waves,The  Vocal  Cords  and  Ear — Wireless  Telephone,  How  Sounds 
Are  Changed  into  Electric  Waves — Wireless  Telephones,  The  Apparatus — Summary. 
154  pages.     156  engravings.    Price $1.50 

WIRING  A  HOUSE.    By  Herbert  Pratt. 

Shows  a  house  already  built;  tells  just  how  to  start  about  wiring  it;  where  to  begin; 
what  wire  to  use;  how  to  run  it  according  to  Insurance  Rules;  in  fact,  just  the  informa- 
tion you  need.     Directions  apply  equally  to  a  shop.    Fourth  edition    ,     ,    35  cents 

18 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 


ELECTROPLATING 

THE  MODERN  ELECTROPLATER.    By  Kenneth  M.  Coggeshall. 

This  is  one  of  the  most  complete  and  practical  books  on  electroplating  and  allied 
processes  that  has  been  published  as  a  text  for  the  student  or  professional  plater. 
It  is  written  in  simple  language  and  explains  all  details  of  electroplating  in  a  concise 
yet  complete  manner.  It  starts  at  the  beginning  and  gives  an  elementary  outline 
of  electricity  and  chemistry  as  relates  to  plating,  then  considers  shop  layout  and 
equipment  and  gives  all  the  necessary  information  to  do  reliable  and  profitable  electro- 
plating in  a  modern  commercial  manner.  Full  instructions  are  given  for  the  prepara- 
tion and  finishing  of  the  work  and  formulae  and  complete  directions  are  included  for 
making  all  kinds  of  plating  solutions,  many  of  these  having  been  trade  secrets  until 
published  in  this  instruction  manual.  Anyone  interested  in  practical  plating  and 
metal  finishing  will  find  this  book  a  valuable  guide  and  complete  manual  of  the  art. 
Cloth.     142  illustrations.     276  pages.     Price $3.00 


FACTORY  MANAGEMENT,  ETC. 

MODERN     MACHINE     SHOP     CONSTRUCTION,     EQUIPMENT     AND 
MANAGEMENT.    By  O.  E.  Perrigo,  M.E. 

The  only  work  published  that  describes  the  modern  machine  shop  or  manufacturing 
plant  from  the  time  the  grass  is  growing  on  the  site  intended  for  it  until  the  finished 
product  is  shipped.  By  a  careful  study  of  its  thirty-six  chapters  the  practical  man 
may  economically  build,  efficiently  equip,  and  successfully  manage  the  modern  machine 
shop  or  manufacturing  establishment.  Just  the  book  needed  by  those  contemplating 
the  erection  of  modern  shop  buildings,  the  rebuilding  and  reorganization  of  old  ones, 
or  the  introduction  of  modern  shop  methods,  time  and  cost  systems.  It  is  a  book 
written  and  illustrated  by  a  practical  shop  man  for  practical  shop  men  who  are  too 
busy  to  read  theories  and  want  facts.  It  is  the  most  complete  all-around  book  of  its 
kind  ever  published.  It  is  a  practical  book  for  practical  men,  from  the  apprentice  in 
the  shop  to  the  president  in  the  office.  It  minutely  describes  and  illustrates  the  most 
simple  and  yet  the  most  efficient  time  and  cost  system  yet  devised.  384  pages.  219 
illustrations.     Price $5.00 


FUEL 

COMBUSTION  OF  COAL  AND  THE  PREVENTION  OF  SMOKE.    By  Wm. 
M.  Barr. 

This  book  has  been  prepared  with  special  reference  to  the  generation  of  heat  by  the 
combustion  of  the  common  fuels  found  in  the  United  States,  and  deals  particularly 
with  the  conditions  necessary  to  the  economic  and  smokeless  combustion  of  bituminous 
Coals  in  Stationary  and  Locomotive  Steam  Boilers. 

The  presentation  of  this  important  subject  is  systematic  and  progressive.  The  ar- 
rangement of  the  book  is  in  a  series  of  practical  questions  to  which  are  appended 
accurate  answers,  which  describe  in  language,  free  from  technicalities,  the  several 
processes  involved  in  the  furnace  combustion  of  American  fuels;  it  clearly  states  the 
essential  requisites  for  perfect  combustion,  and  points  out  the  best  methods  for  furnace 
construction  for  obtaining  the  greatest  quantity  of  heat  from  any  given  quality  of 
coal.    5th  Edition.     Nearly  350  pages,  fully  illustrated.     Price.      .      .      .     $1.50 

19 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 


GAS  AND  OIL  ENGINES 

THE   GASOLINE   ENGINE   ON  THE  FARM:  ITS  OPERATION,  REPAIR 
AND  USES.    By  Xeno  W.  Putnam. 

This  is  a  practical  treatise  on  the  Gasoline  and  Kerosene  Engine  intended  for  the  man 
who  wants  to  know  just  how  to  manage  his  engine  and  how  to  apply  it  to  all  kinds  of 
farm  work  to  the  best  advantage. 

This  book  abounds  with  hints  and  helps  for  the  farm  and  suggestions  for  the  home 
and  housewife.  There  is  so  much  of  value  in  this  book  that  it  is  impossible  to  ade- 
quately describe  it  in  such  small  space.  Suffice  to  say  that  it  is  the  kind  of  a  book 
every  farmer  will  appreciate  and  every  farm  home  ought  to  have.  Includes  selecting 
the  most  suitable  engine  for  farm  work,  its  most  convenient  and  efficient  installation, 
with  chapters  on  troubles,  their  remedies,  and  how  to  avoid  them.  The  care  and 
management  of  the  farm  tractor  in  plowing,  harrowing,  harvesting  and  road  grading 
are  fully  covered;  also  plain  directions  are  given  for  handling  the  tractor  on  the  road. 
Special  attention  is  given  to  relieving  farm  life  of  its  drudgery  by  applying  power  to 
the  disagreeable  small  tasks  which  must  otherwise  be  done  by  hand.  Many  home- 
made contrivances  for  cutting  wood,  supplying  kitchen,  garden,  and  barn  with  water, 
loading,  hauling  and  unloading  hay,  delivering  grain  to  the  bins  or  the  feed  trough 
are  included;  also  full  directions  for  making  the  engine  milk  the  cows,  churn,  wash, 
sweep  the  house  and  clean  the  windows,  etc.  Very  fully  illustrated  with  drawings  of 
working  parts  and  cuts  showing  Stationary,  Portable  and  Tractor  Engines  doing  all 
kinds  of  farm  work.  All  money-making  farms  utilize  power.  Learn  how  to  utilize 
power  by  reading  the  pages  of  this  book.  It  is  an  aid  to  the  result  getter,  invaluable 
to  the  up-to-date  farmer,  student,  blacksmith,  implement  dealer  and,  in  fact,  all  who 
can  apply  practical  knowledge  of  stationary  gasoline  engines  or  gas  tractors  to  advan- 
tage.    530  pages.     Nearly  180  engravings.    Price $3.00 

GASOLINE  ENGINES :  THEIR  OPERATION,  USE  AND  CARE.    By  A.  Hyatt 
Verrill. 

The  simplest,  latest  and  most  comprehensive  popular  work  published  on  Gasoline 
Engines,  describing  what  the  Gasoline  Engine  is;  its  construction  and  operation;  how 
to  install  it;  how  to  select  it;  how  to  use  it  and  how  to  remedy  troubles  encountered. 
Intended  for  Owners,  Operators  and  Users  of  Gasoline  Motors  of  all  kinds.  This 
work  fully  describes  and  illustrates  the  various  types  of  Gasoline  Engines  used  in 
Motor  Boats,  Motor  Vehicles  and  Stationary  Work.  The  parts,  accessories  and 
appliances  are  described,  with  chapters  on  ignition,  fuel,  lubrication,  operation  and 
engine  troubles.  Special  attention  is  given  to  the  care,  operation  and  repair  of  motors, 
with  useful  hints  and  suggestions  on  emergency  repairs  and  makeshifts.  A  complete 
glossary  of  technical  terms  and  an  alphabetically  arranged  table  of  troubles  and  their 
symptoms  form  most  valuable  and  unique  features  of  this  manual.  Nearly  every 
illustration  in  the  book  is  original,  having  been  made  by  the  author.  Every  page  is 
full  of  interest  and  value.  A  book  which  you  cannot  afford  to  be  without.  275  pages. 
152  specially  made  engravings.    Price $2.00 

GAS,  GASOLINE,  AND  OIL  ENGINES.    By  Gardner  D.  Hiscox. 

Just  issued,  23d  revised  and  enlarged  edition.  Every  user  of  a  gas  engine  needs  this 
book.  Simple,  instructive,  and  right  up-to-date.  The  only  complete  work  on  the 
subject.  Tells  all  about  the  running  and  management  of  gas,  gasoline  and  oil  engines, 
as  designed  and  manufactured  in  the  United  States.  Explosive  motors  for  stationary 
marine  and  vehicle  power  are  fully  treated,  together  with  illustrations  of  their  parts 
and  tabulated  sizes,  also  their  care  and  running  are  included.  Electric  ignition  by 
induction  coil  and  jump  spark  are  fully  explained  and  illustrated,  including  valuable 
information  on  the  testing  for  economy  and  power  and  the  erection  of  power  plants. 

The  rules  and  regulations  of  the  Board  of  Fire  Underwriters  in  regard  to  the  installation 
and  management  of  gasoline  motors  are  given  in  full,  suggesting  the  safe  installation 
of  explosive  motor  power.  A  list  of  United  States  Patents  issued  on  gas,  gasoline,  and 
oil  engines  and  their  adjuncts  from  1875  to  date  is  included.  640  pages.  435  engrav- 
ings.   Folding  plates.    Price $3.00 

20 


CATALOGUE   OF  GOOD,  PRACTICAL  BOOKS 

GAS  ENGINES  ANDtePRODUCER-GAS  PLANTS.    By  R.  E.  Mathot,  M.E. 

This  is  a  practical  treatise,  setting  forth  the  principles  of  gas  engine  and  producer 
design,  the  selection  and  installation  of  an  engine,  conditions  of  perfect  operation, 
producer-gas  engines  and  their  possibilities ;  the  care  of  gas  engines  and  producer-gas 
plants,  with  a  chapter  on  volatile  hydrocarbon  and  oil  engines.  A  practical  guide  for 
the  gas  engine  designer,  user  and  engineer  in  the  construction,  selection,  purchase,  in- 
stallation, operation  and  maintenance  of  gas  engines.  Every  part  of  the  gas  engine  is  de- 
scribed in  detail,  tersely,  clearly  and  with  a  thorough  understanding  of  the  requirements  of 
the  mechanic.  Recognizing  the  need  of  a  volume  that  would  assist  the  gas  engine 
user  in  understanding  the  motor  upon  which  he  depends  for  power,  the  author  has 
discussed  the  subject  without  the  help  of  any  mathematics.  Helpful  suggestions  as  to 
the  purchase  of  an  engine,  its  installation,  care  and  operation,  form  a  most  valuable 
feature  of  the  book.    6x9inches.    Cloth.   314  pages.    152  illustrations.    Price..  $3 .00 

GAS  ENGINE  CONSTRUCTION,  OR  HOW  TO  BUILD  A  HALF-HORSE- 
POWER GAS  ENGINE.    By  Parsell  and  Weed. 

A  practical  treatise  of  300  pages  describing  the  theory  and  principles  of  the  action  of 
Gas  Engines  of  various  types  and  the  design  and  construction  of  a  half-horse-power 
Gas  Engine,  with  illustrations  of  the  work  in  actual  progress,  together  with  the  dimen- 
sioned working  drawings,  giving  clearly  the  sizes  of  the  various  details ;  for  the  student, 
the  scientific  investigator,  and  the  amateur  mechanic.  This  book  treats  of  the  subject 
more  from  the  standpoint  of  practice  than  that  of  theory.  The  principles  of  operation 
of  Gas  Engines  are  clearly  and  simply  described,  and  then  the  actual  construction  of  a 
half-horse-power  engine  is  taken  up,  step  by  step,  showing  in  detail  the  making  of  the 
Gas  Engine.     3d  Edition.     300  pages.     Price $3.00 

HOW  TO  RUN  AND  INSTALL  GASOLINE  ENGINES.    By  C.  Von  Culin. 

Eevised  and  enlarged  edition  just  issued.  The  object  of  this  little  book  is  to  furnish 
a  pocket  instructor  for  the  beginner,  the  busy  man  who  uses  an  engine  for  pleasure  or 
profit,  but  who  does  not  have  the  time  or  inclination  for  a  technical  book,  but  simply 
to  thoroughly  understand  how  to  properly  operate,  install  and  care  for  his  own  engine. 
The  index  refers  to  each  trouble,  remedy,  and  subject  alphabetically.  Being  a  quick 
reference  to  find  the  cause,  remedy  and  prevention  for  troubles,  and  to  become  an 
expert  with  his  own  engine.    Pocket  size.    Paper  binding.    Price      ,     ,     25  cents 

GEARING  AND  CAMS 


BEVEL  GEAR  TABLES.    By  D.  Ag.  Engstrom. 

A  book  that  will  at  once  commend  itself  to  mechanics  and  draftsmen.  Does  away 
with  all  the  trigonometry  and  fancy  figuring  on  bevel  gears,  and  makes  it  easy  for  any- 
one to  lay  them  out  or  make  them  just  right.  There  are  36  full-page  tables  that 
show  every  necessary  dimension  for  all  sizes  or  combinations  you're  apt  to  need.  No 
puzzling,  figuring  or  guessing.  Gives  placing  distance,  all  the  angles  (including 
cutting  angles),  and  the  correct  cutter  to  use.  A  copy  of  this  prepares  you  for  any- 
thing in  the  bevel-gear  line.     3d  Edition.     66  pages $1.50 

CHANGE  GEAR  DEVICES.    By  Oscar  E.  Perrigo. 

A  practical  book  for  every  designer,  draftsman,  and  mechanic  interested  in  the  inven- 
tion and  development  of  the  devices  for  feed  changes  on  the  different  machines  requir- 
ing such  mechanism.  All  the  necessary  information  on  this  subject  is  taken  up, 
analyzed,  classified,  sifted,  and  concentrated  for  the  use  of  busy  men  who  have  not  the 
time  to  go  through  the  masses  of  irrelevant  matter  with  which  such  a  subject  is  usu- 
ally encumbered  and  select  such  information  as  will  be  useful  to  them. 

It  shows  just  what  has  been  done,  how  it  has  been  done,  when  it  was  done,  and  who 
did  it.  It  saves  time  in  hunting  up  patent  records  and  re-inventing  old  ideas.  3rd 
Edition.     101  pages $1.50 

DRAFTING  OF  CAMS.    By  Louis  Rottillion. 

The  laying  out  of  cams  is  a  serious  problem  unless  you  know  how  to  go  at  it  right. 
This  puts  you  on  the  right  road  for  practically  any  kind  of  cam  you  are  likely  to  run 
up  against.    3d  Edition, ,,,.......,    35  centf 

21 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 

Mi 


HYDRAULICS 

HYDRAULIC  ENGINEERING.    By  Gardner  D.  Hiscox. 

A  treatise  on  the  properties,  power,  and  resources  of  water  for  all  purposes.  Including 
the  measurement  of  streams,  the  flow  of  water  in  pipes  or  conduits;  the  horse-power 
of  falling  water,  turbine  and  impact  water-wheels,  wave  motors,  centrifugal,  recipro- 
cating and  air-lift  pumps.  With  300  figures  and  diagrams  and  36  practical  tables. 
All  who  are  interested  in  water-works  development  will  find  this  book  a  useful  ono, 
because  it  is  an  entirely  practical  treatise  upon  a  subject  of  present  importance,  and 
cannot  fail  in  having  a  far-reaching  influence,  and  for  this  reason  should  have  a  place 
in  the  working  library  of  every  engineer.  Among  the  subjects  treated  are:  Historical 
Hydraulics,  Properties  of  Water,  Measurement  of  the  Flow  of  Streams;  Flow- 
ing Water  Suface  Orifices  and  Nozzles ;  Flow  of  Water  in  Pipes ;  Siphons  of  Various 
Kinds;  Dams  and  Great  Storage  Reservoirs;  City  and  Town  Water  Supply;  Wells 
and  Their  Reinforcement;  Air  Lift  Methods  of  Raising  Water;  Artesian  Wells, 
Irrigation  of  Arid  Districts;  Water  Power;  Water- Wheels ;  Pumps  and  Pumping 
Machinery;  Reciprocating  Pumps;  Hydraulic  Power  Transmission;  Hydraulic 
Mining;  Canals;  Dredges;  Conduits  and  Pipe  Lines;  Marine  Hydraulics;  Tidal  and 
Sea  Wave  Power,  etc.    320  pages.    Price $4.50 


ICE  AND  REFRIGERATION 


POCKETBOOK    OF   REFRIGERATION    AND    ICE    MAKING.    By   A.    J. 

Wallis-Taylor. 

This  is  one  of  the  latest  and  most  comprehensive  reference  books  published  on  the 
subject  of  refrigeration  and  cold  storage.  It  explains  the  properties  and  refrigerating 
effect  of  the  different  fluids  in  use,  the  management  of  refrigerating  machinery  and  the 
construction  and  insulation  of  cold  rooms  with  their  required  pipe  surface  for  different 
degrees  of  cold ;  freezing  mixtures  and  non-freezing  brines,  temperatures  of  cold  rooms 
for  all  kinds  of  provisions,  cold  storage  charges  for  all  classes  of  goods,  ice  making 
and  storage  of  ice,  data  and  memoranda  for  constant  reference  by  refrigerating  engineers, 
with  nearly  one  hundred  tables  containing  valuable  references  to  every  fact  and  con- 
dition required  in  the  installment  and  operation  of  a  refrigerating  plant.  New 
edition  just  published.     Price $2.00 


INVENTIONS— PATENTS 

INVENTORS'  MANUAL,  HOW  TO  MAKE  A  PATENT  PAY. 

This  is  a  book  designed  as  a  guide  to  inventors  in  perfecting  their  inventions,  taking 
out  their  patents  and  disposing  of  them.  It  is  not  in  any  sense  a  Patent  Solicitor's 
Circular  nor  a  Patent  Broker's  Advertisement.  No  advertisements  of  any  description 
appear  in  the  work.  It  is  a  book  containing  a  quarter  of  a  century's  experience  of  a 
successful  inventor,  together  with  notes  based  upon  the  experience  of  many  other 
inventors. 

Among  the  subjects  treated  in  this  work  are:  How  to  Invent.  How  to  Secure  a 
Good  Patent.  Value  of  Good  Invention.  How  to  Exhibit  an  Invention.  How  to 
Interest  Capital.  How  to  Estimate  the  Value  of  a  Patent.  Value  of  Design  Patents. 
Value  of  Foreign  Patents.  Value  of  Small  Inventions.  Advice  on  Selling  Patents. 
Advice  on  the  Formation  of  Stock  Companies.  Advice  on  the  Formation  of  Limited 
Liability  Companies.  Advice  on  Disposing  of  Old  Patents.  Advice  as  to  Patent 
Attorneys.  Advice  as  to  Selling  Agents.  Forms  of  Assignments.  License  and  Con- 
tracts. State  Laws  Concerning  Patent  Rights.  1900  Census  of  the  United  States  by 
Counts  of  Over  10,000  Population.  New  revised  and  enlarged  edition.  144  pages. 
Illustrated.   Price.     ,    ,     .- - ,..,,,,«    $1.50 

33 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 


KNOTS 

KNOTS,  SPLICES  AND  ROPE  WORK.    By  A.  Hyatt  Verrill. 

This  is  a  practical  book  giving  complete  and  simple  directions  for  making  all  the  most 
useful  and  ornamental  knots  in  common  use,  with  chapters  on  Splicing,  Pointing, 
Seizing,  Serving,  etc.  This  book  is  fully  illustrated  with  one  hundred  and  fifty 
original  engravings,  which  show  how  each  knot,  tie  or  splice  is  formed,  and  its  appear- 
ance when  finished.  The  book  will  be  found  of  the  greatest  value  to  Campers,  Yachts- 
men, Travelers,  Boy  Scouts,  in  fact,  to  anyone  having  occasion  to  use  or  handle  rope 
or  knots  for  any  purpose.  The  book  is  thoroughly  reliable  and  practical,  and  is  not 
only  a  guide,  but  a  teacher.  It  is  the  standard  work  on  the  subject.  Among  the 
contents  are:  1.  Cordage,  Kinds  of  Rope.  Construction  of  Rope,  Parts  of  Rope 
Cable  and  Bolt  Rope.  Strength  of  Rope,  Weight  of  Rope.  2.  Simple  Knots  ana 
Bends.  Terms  Used  in  Handling  Rope.  Seizing  Rope.  3.  Ties  and  Hitches.  4. 
Noose,  Loops  and  Mooring  Knots.  5.  Shortenings,  Grommets  and  Salvages.  6. 
Lashings,  Seizings  and  Splices.  7.  Fancy  Knots  and  Rope  Work.  104  pages.  154 
original  engravings.    Price $1.00 

LATHE  WORK 

LATHE  DESIGN,  CONSTRUCTION,  AND  OPERATION,  WITH  PRACTICAL 
EXAMPLES  OF  LATHE  WORK.    By  Oscar  E.  Perrigo. 

A  new  revised  edition,  and  the  only  complete  American  work  on  the  subject,  written 
by  a  man  who  knows  not  only  how  work  ought  to  be  done,  but  who  also  knows  how 
to  do  it,  and  now  to  convey  this  knowledge  to  others.  It  is  strictly  up-to-date  in  its 
descriptions  and  illustrations.  Lathe  history  and  the  relations  of  the  lathe  to  manu- 
facturing are  given;  also  a  description  of  the  various  devices  for  feeds  and  thread 
cutting  mechanisms  from  early  efforts  in  this  direction  to  the  present  time.  Lathe 
design  is  thoroughly  discussed,  including  back  gearing,  driving  cones,  thread-cutting 
gears,  and  all  the  essential  elements  of  the  modern  lathe.  The  classification  of  lathes 
is  taken  up,  giving  the  essential  differences  of  the  several  types  of  lathes  including, 
as  is  usually  understood,  engine  lathes,  bench  lathes,  speed  lathes,  forge  lathes,  gap 
lathes,  pulley  lathes,  forming  lathes,  multiple-spindle  lathes,  rapid-reduction  lathes, 
precision  lathes,  turret  lathes,  special  lathes,  electrically-driven  lathes,  etc.  In  addi- 
tion to  the  complete  exposition  on  construction  and  design,  much  practical  matter  on 
lathe  installation,  care  and  operation  has  been  incorporated  in  the  enlarged  1915  edi- 
tion. All  kinds  of  lathe  attachments  for  drilling,  milling,  etc.,  are  described  and 
complete  instructions  are  given  to  enable  the  novice  machinist  to  grasp  the  art  of  lathe 
operation  as  well  as  the  principles  involved  in  design.  A  number  of  difficult  machining 
operations  are  described  at  length  and  illustrated.  The  new  edition  has  nearly  500 
pages  and  350  illustrations.     Price      .  ,     $3.00 

LATHE  WORK  FOR  BEGINNERS.    By  Raymond  Francis  Yates. 

A  simple,  straightforward  text-book  for  those  desiring  to  learn  the  operation  of  a 
wood-turning  or  metal-turning  lathe.  The  first  chapter  tells  how  to  choose  a  lathe 
and  all  of  the  standard  types  on  the  market  are  described.  Simple  and  more  advanced 
lathe  work  is  thoroughly  covered  and  the  operation  of  all  lathe  attachments  such  as 
millers,  grinders,  polishers,  etc.,  is  described.  The  treatment  starts  from  the  very 
bottom  and  leads  the  reader  through  to  a  point  where  he  will  be  able  to  handle  the 
larger  commercial  machines  with  very  little  instruction.  The  last  chapter  of  the 
book  is  devoted  to  things  to  make  on  the  lathe  and  includes  a  model  rapid-fire  naval 
gun.  This  is  the  only  book  published  in  this  country  that  treats  lathe  work  from 
the  standpoint  of  the  amateur  mechanic.  162  illustrations.  About  250  pages,  12mo. 
Price $2.00 

TURNING  AND  BORING  TAPERS.    By  Fred  H.  Colvin. 

There  are  two  ways  to  turn  tapers;  the  right  way  and  one  other.  This  treatise  has 
to  do  with  the  right  way;  it  tells  you  how  to  start  the  work  properly,  how  to  set  the 
lathe,  what  tools  to  use  and  how  to  use  them,  and  forty  and  one  other  little  things 
that  you  should  know.    Fifth  edition.    Price        ....,.,,,     35  cents 

23 


CATALOGUE   OF   GOOD,  PRACTICAL  BOOKS 


LIQUID  AIR 

LIQUID  AIR  AND  THE  LIQUEFACTION  OF  GASES.  By  T.  O'Conor  Sloane. 

This  book  gives  the  history  of  the  theory,  discovery,  and  manufacture  of  Liquid  Air, 
and  contains  an  illustrated  description  of  all  the  experiments  that  have  excited  the 
wonder  of  audiences  all  over  the  country.  It  shows  how  liquid  air,  like  water,  is 
carried  hundreds  of  miles  and  is  handled  in  open  buckets.  It  tells  what  may  be  ex- 
pected from  it  in  the  near  future. 

A  book  that  renders  simple  one  of  the  most  perplexing  chemical  problems  of  the 
century.     Startling  developments  illustrated  by  actual  experiments. 

It  is  not  only  a  work  of  scientific  interest  and  authority,  but  is  intended  for  the  general 
reader,  being  written  in  a  popular  style — easily  understood  by  everyone.  Third 
edition.     Revised  and  Enlarged.     394  pages.     New  Edition.    Price    .     .     .     $3.00 

LOCOMOTIVE  ENGINEERING 


AIR-BRAKE  CATECHISM.    By  Robert  H.  Blackall. 

This  book  is  a  standard  text-book.  It  covers  the  Westinghouse  Air-Brake  Equipment, 
including  the  No.  5  and  the  No.  6  E.  T.  Locomotive  Brake  Equipment;  the  K  (Quick 
Service)  Triple  Valve  for  Freight  Service;  and  the  Cross-Compound  Pump.  The 
operation  of  all  parts  of  the  apparatus  is  explained  in  detail,  and  a  practical  way  of 
finding  their  peculiarities  and  defects,  with  a  proper  remedy,  is  given.  It  contains 
2,000  questions  with  their  answers,  which  will  enable  any  railroad  man  to  •  pass  any 
examination  on  the  subject  of  Air  Brakes.  Endorsed  and  used  by  air-brake  instruc- 
tors and  examiners  on  nearly  every  railroad  in  the  United  States.  28th  Edition.  411 
pages,  fully  illustrated  with  colored  plates  and  diagrams.     Price $2.50 

COMBUSTION  OF  COAL  AND  THE  PREVENTION  OF  SMOKE.    By  Wm. 

M.  Barr. 

This  book  has  been  prepared  with  special  reference  to  the  generation  of  heat  by  the 
combustion  of  the  common  fuels  found  in  the  United  States  and  deals  particularly 
with  the  conditions  necessary  to  the  economic  and  smokeless  combustion  of  bituminous 
coal  in  Stationary  and  Locomotive  Steam  Boilers. 

Presentation  of  this  important  subject  is  systematic  and  progressive.  The  ar- 
rangement of  the  book  is  in  a  series  of  practical  questions  to  which  are  appended 
accurate  answers,  which  describe  in  language  free  from  technicalities  the  several 
processes  involved  in  the  furnace  combustion  of  American  fuels;  it  clearly  states  the 
essential  requisites  for  perfect  combustion,  and  points  out  the  best  methods  of  furnace 
construction  for  obtaining  the  greatest  quantity  of  heat  from  any  given  quality  of 
coal.     Nearly  350  pages,  fully  illustrated.     Price $1.50 

DIARY  OF  A  ROUND-HOUSE  FOREMAN.    By  T.  S.  Reilly. 

This  is  the  greatest  book  of  railroad  experiences  ever  published.  Containing  a  fund  of 
information  and  suggestions  along  the  line  of  handling  men,  organizing,  etc.,  that  one 
cannot  afford  to  miss.     158  pages.     Price $1.50 

LINK  MOTIONS,  VALVES  AND  VALVE  SETTING.    By  Fred  H.  Colvin, 

Associate  Editor  of  American  Machinist. 

A  handy  book  for  the  engineer  or  machinist  that  clears  up  the  mysteries  of  valve 
setting.  Shows  the  different  valve  gears  in  use,  how  they  work,  and  why.  Piston 
and  slide  valves  of  different  types  are  illustrated  and  explained.  A  book  that  every 
railroad  man  in  the  motive  power  department  ought  to  have.  Contains  chapters  on 
Locomotive  Link  Motion,  Valve  Movements,  Setting  Slide  Valves,  Analysis  by 
Diagrams,  Modern  Practice,  Slip  of  Block,  Slice  Valves,  Piston  Valves,  Setting  Piston 
Valves,  Joy-Allen  Valve  Gear,  Walschaert  Valve  Gear,  Gooch  Valve  Gear,  Alfree- 
Hubbell  Valve  Gear,  etc.,  etc.     3rd  Edition,  101  »ages.     Fully  illustrated.     Price 

75  cents 

24 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 

LOCOMOTIVE  BOILER  CONSTRUCTION.    By  Frank  A.  Kleinhans. 

The  construction  of  boilers  in  general  is  treated,  and,  following  this,  the  locomotive 
boiler  is  taken  up  in  the  order  in  which  its  various  parts  go  through  the  shop.  Shows 
all  types  of  boilers  used;  gives  details  of  construction;  practical  facts,  such  as  life  of 
riveting,  punches  and  dies;  work  done  per  day,  allowance  for  bending  and  flanging 
sheets,  and  other  data.  Including  the  recent  Locomotive  Boiler  Inspection  Laws 
and  Examination  Questions  with  their  answers  for  Government  Inspectors.  Contains 
chapters  on  Laying  Out  Work;  Flanging  and  Forging;  Punching;  Shearing;  Plate 
Planing;  General  Tables;  Finishing  Parts;  Bending;  Machinery  Parts;  Riveting; 
Boiler  Details;  Smoke  Box  Details;  Assembling  and  Calking;  Boiler  Shop 
Machinery,  etc.,  etc. 

There  isn't  a  man  who  has  anything  to  do  with  boiler  work,  either  new  or  repair  work, 
who  doesn't  need  this  book.  The  manufacturer,  superintendent,  foreman,  and  boiler 
worker — all  need  it.  No  matter  what  the  type  of  boiler,  you'll  find  a  mint  of  informa- 
tion that  you  wouldn't  be  without.  451  pages,  334  illustrations,  five  large  folding 
plates.     Price $3.50 

LOCOMOTIVE  BREAKDOWNS  AND  THEIR  REMEDIES.  By  Geo.  L. 
Fowler.  Revised  by  Wm.  W.  Wood,  Air-Brake  Instructor.  Just  issued. 
Revised  pocket  edition. 

It  is  out  of  the  question  to  try  and  tell  you  about  every  subject  that  is  covered  in  this 
pocket  edition  of  Locomotive  Breakdowns.  Just  imagine  all  the  common  troubles 
that  an  engineer  may  expect  to  happen  some  time,  and  then  add  all  of  the  unexpected 
ones,  troubles  that  could  occur,  but  that  you  have  never  thought  about,  and  you  will 
find  that  they  are  all  treated  with  the  very  best  methods  of  repahr.  Walschaert 
Locomotive  Valve  Gear  Troubles,  Electric  Headlight  Troubles,  as  well  as  Questions 
and  Answers  on  the  Air  Brake  are  all  included.  293  pages.  8th  Revised  Edition. 
Fully  illustrated. $1.50 

PRACTICAL  INSTRUCTOR  AND  REFERENCE  BOOK  FOR  LOCOMOTIVE 
FIREMEN  AND  ENGINEERS.    By  Chas.  F.  Lockhabt. 

An  entirely  new  book  on  the  Locomotive.  It  appeals  to  every  railroad  man,  as  it 
tells  him  how  things  are  done  and  the  right  way  to  do  them.  Written  by  a  man  who 
has  had  years  of  practical  experience  in  locomotive  shops  and  on  the  road  firing  and 
running.  The  information  given  in  this  book  cannot  be  found  in  any  other  similar 
treatise.  Eight  hundred  and  fifty-one  questions  with  their  answers  are  included, 
which  will  prove  specially  helpful  to  those  preparing  for  examination.  Practical 
information  on:  The  Construction  and  Operation  of  Locomotives;  Breakdowns  and 
their  Remedies;  Air  Brakes  and  Valve  Gears.  Rules  and  Signals  are  handled  in  a 
thorough  manner.  As  a  book  of  reference  it  cannot  be  excelled.  The  book  is  divided 
into  six  parts,  as  follows:  1.  The  Fireman's  Duties.  2.  General  Description  of  the 
Locomotive.  3.  Breakdowns  and  their  Remedies.  4.  Air  Brakes.  5.  Extracts 
from  Standard  Rules.  6.  Questions  for  Examination,  The  851  questions  have  been 
carefully  selected  and  arranged.  These  cover  the  examinations  required  by  the 
different  railroads.     368  pages.     88  illustrations.     Price $2.50 

PREVENTION  OF  RAILROAD  ACCIDENTS,  OR  SAFETY  IN  RAILROADING. 

By  George  Bradshaw. 

This  book  is  a  heart-to-heart  talk  with  Railroad  Employees,  dealing  with  facts,  not 
theories,  and  showing  the  men  in  the  ranks,  from  every-day  experience,  how  accidents 
occur  and  how  they  may  be  avoided.  The  book  is  illustrated  with  seventy  original 
photographs  and  drawings  showing  the  safe  and  unsafe  methods  of  work.  No  vision- 
ary schemes,  no  ideal  pictures.  Just  plain  facts  and  Practical  Suggestions  are  given. 
Every  railroad  employee  who  reads  the  book  is  a  better  and  safer  man  to  have  in 
railroad  service.  It  gives  just  the  information  which  will  be  the  means  of  preventing 
many  injuries  and  deaths.  All  railroad  employees  should  procure  a  copy;  read  it, 
and  do  your  part  in  preventing  accidents.  169  pages.  Pocket  size.  Fully  illustrated. 
Price - 50  cents 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 

TRAIN  RULE  EXAMINATIONS  MADE  EASY.    By  G.  E.  Collingwood. 

This  is  the  only  practical  work  on  train  rules  in  print.  Every  detail  is  covered,  and 
puzzling  points  are  explained  in  simple,  comprehensive  language,  making  it  a  practical 
treatise  for  the  Train  Dispatcher,  Engineman,  Trainman,  and  all  others  who  have  to 
do  with  the  movements  of  trains.  Contains  complete  and  reliable  information  of  the 
Standard  Code  of  Train  Rules  for  single  track.  Shows  Signals  in  Colors,  as  used  on 
the  different  roads.  Explains  fully  the  practical  application  of  train  orders,  giving  a 
clear  and  definite  understanding  of  all  orders  which  may  be  used.  The  meaning  and 
necessity  for  certain  rules  are  explained  in  such  a  manner  that  the  student  may  know 
beyond  a  doubt  the  rights  conferred  under  any  orders  be  may  receive  or  the  action 
required  by  certain  rules.  <  As  nearly  all  roads  require  trainmen  to  pass  regular  exami- 
nations, a  complete  set  of  examination  questions,  with  their  answers,  are  included. 
These  will  enable  the  student  to  pass  the  required  examinations  with  credit  to  himself 
and  the  road  for  which  he  works.  Second  Edition  revised.  234  pages.  Fully  illus- 
trated with  Train- Signals  in  Colors.     Price $1.50 

THE  WALSCHAERT  AND  OTHER  MODERN  RADIAL  VALVE  GEARS  FOR 
LOCOMOTIVES.    By  Wm.  W.  Wood. 

If  you  would  thoroughly  understand  the  "Walschaert  Valve  Gear  you  should  possess  a 
copy  of  this  book,  as  the  author  takes  the  plainest  form  of  a  steam  engine — a  stationary 
engine  in  the  rough,  that  will  only  turn  its  crank  in  one  direction — and  from  it  builds 
tip — with  the  reader's  help — a  modern  locomotive  equipped  with  the  Walschaert 
Valve  Gear,  complete.  The  points  discussed  are  clearly  illustrated;  two  large  folding 
plates  that  show  the  positions  of  the  valves  of  both  inside  or  outside  admission  type,  as 
well  as  the  links  and  other  parts  of  the  gear  when  the  crank  is  at  nine  different  points 
in  its  revolution,  are  especially  valuable  in  making  the  movement  clear.  These  employ 
sliding  cardboard  models  which  are  contained  in  a  pocket  in  the  cover. 

The  book  is  divided  into  five  general  divisions,  as  follows:  1.  Analysis  of  the  gear. 
2.  Designing  and  erecting  the  gear.  3.  Advantages  of  the  gear.  4.  Questions  and 
answers  relating  to  the  Walschaert  Valve  Gear.  5.  Setting  valves  with  the  Wal- 
schaert Valve  Gear;  the  three  primary  types  of  locomotive  valve  motion;  modern 
radial  valve  gears  other  than  the  Walschaert;  the  Hobart  All-free  Valve  and  Valve 
Gear,  with  questions  and  answers  on  breakdowns;  the  Baker-Pilliod  Valve  Gear;  the 
Improved  Baker-Pilliod  Valve  Gear,  with  questions  and  answers  on  breakdowns. 

The  questions  with  full  answers  given  will  be  especially  valuable  to  firemen  and  engi- 
neers in  preparing  for  an  examination  for  promotion.  245  pages.  Fully  illustrated. 
Third  Revised  New  Edition.     Price $2.50 

WESTINGHOUSE  E-T  AIR-BRAKE  INSTRUCTION  POCKET  BOOK.    By 

Wm.  W.  Wood,  Air-Brake  Instructor. 

Here  is  a  book  for  the  railroad  man,  and  the  man  who  aims  to  be  one.  It  is  without 
doubt  the  only  complete  work  published  on  the  Westinghouse  E-T  Locomotive  Brake 
Equipment.  Written  by  an  Air-Brake  Instructor  who  knows  just  what  is  needed.  It 
covers  the  subject  thoroughly.  Everything  about  the  New  Westinghouse  Engine  and 
Tender  Brake  Equipment,  including  the  standard  No.  5  and  the  Perfected  No.  6 
style  of  brake,  is  treated  in  detail.  Written  in  plain  English  and  profusely  illustrated 
with  Colored  Plates,  which  enable  one  to  trace  the  flow  of  pressures  throughout  the 
entire  equipment.  The  best  book  ever  published  on  the  Air  Brake.  Equally  good  for 
the  beginner  and  the  advanced  engineer.  Will  pass  anyone  through  any  examination. 
It  informs  and  enlightens  you  on  every  point.  Indispensable  to  every  engineman  and 
trainman. 

Contains  examination  questions  and  answers  on  the  E-T  equipment.  Covering  what 
the  E-T  Brake  is.  How  it  should  be  operated.  What  to  do  when  defective.  Not  a 
question  can  be  asked  of  the  engineman  up  for  promotion,  on  either  the  No.  5  or  the 
No.  6  E-T  equipment,  that  is  not  asked  and  answered  in  the  book.  If  you  want  to 
thoroughly  understand  the  E-T  equipment  get  a  copy  of  this  book.  It  covers  every 
detail.  Makes  Air-Brake  troubles  and  examinations  easy.  Second  Revised  and 
Enlarged  Edition.     Price $2.50 


26 


CATALOGUE   OF  GOOD,  PRACTICAL  BOOKS 


MACHINE-SHOP  PRACTICE 

AMERICAN  TOOL  MAKING  AND  INTERCHANGEABLE  MANUFACTUR- 
ING.   By  J.  V.  Woodworth. 

A  "shoppy"  book,  containing  no  theorizing,  no  problematical  or  experimental  devices, 
there  are  no  badly  proportioned  and  impossible  diagrams,  no  catalogue  cuts,  but  a 
valuable  collection  of  drawings  and  descriptions  of  devices,  the  rich  fruits  of  the  author's 
own  experience.  In  its  500-odd  pages  the  one  subject  only,  Tool  Making,  and  what- 
ever relates  thereto,  is  dealt  with.  The  work  stands  without  a  rival.  It  is  a  complete 
practical  treatise  on  the  art  of  American  Tool  Making  and  system  of  interchangeable 
manufacturing  as  carried  on  to-day  in  the  United  States.  In  it  are  described  and 
illustrated  all  of  the  different  types  and  classes  of  small  tools,  fixtures,  devices,  and 
special  appliances  which  are  in  general  use  in  all  machine-manufacturing  and  metal- 
working  establishments  where  economy,  capacity,  and  interchangeability  in  the  pro- 
duction of  machined  metal  parts  are  imperative.  The  science  of  jig  making  is  exhaus- 
tively discussed,  and  particular  attention  is  paid  to  drill  jigs,  boring,  profiling  and  milling 
fixtures  and  other  devices  in  which  the  parts  to  be  machined  are  located  and  fastened 
within  the  contrivances.  All  of  the  tools,  fixtures,  and  devicas  illustrated  and  de- 
scribed have  been  or  are  used  for  the  actual  production  of  work,  such  as  parts  of  drill 
presses,  lathes,  patented  machinery,  typewriters,  electrical  apparatus,  mechanical  ap- 
pliances, brass  goods,  composition  parts,  mould  products,  sheet  metal  articles,  drop- 
forgings,  jewelry,  watches,  medals,  coins,  etc.     3rd  Edition*    531  pages.     Price  $4.50 

MACHINE-SHOP  ARITHMETIC.    By  Colvin-Cheney.: 

This  is  an  arithmetic  of  the  things  you  have  to  do  with  daily.  It  tells  you  plainly 
about:  how  to  find  areas  in  figures;  how  to  find  surface  or  volume  of  balls  or  spheres; 
handy  ways  for  calculating;  about  compound  gearing;  cutting  screw  threads  on  any 
lathe;  drilling  for  taps;  speeds  of  drills;  taps,  emery  wheels,  grindstones,  milling 
cutters,  etc.;  all  about  the  Metric  system  with  conversion  tables;  properties  of  metals; 
strength  of  bolts  and  nuts;  decimal  equivalent  of  an  inch.  All  sorts  of  machine-shop 
figuring  and  1,001  other  things,  any  one  of  which  ought  to  be  worth  more  than 
the  price  of  this  book  to  you,  and  it  saves  you  the  trouble  of  bothering  the  boss.  7th 
edition.     131  pages.    Price 75  cents 

MODERN  MACHINE-SHOP  CONSTRUCTION,  EQUIPMENT  AND  MAN- 
AGEMENT.   By  Oscar  E.  Perrigo. 

The  only  work  published  that  describes  the  Modern  Shop  or  Manufacturing  Plant 
from  the  time  the  grass  is  growing  on  the  site  intended  for  it  until  the  finished  product 
is  shipped.  Just  the  book  needed  by  those  contemplating  the  erection  of  modern  shop 
buildings,  the  rebuilding  and  reorganization  of  old  ones,  or  the  introduction  of  Modern 
Shop  Methods,  time  and  cost  systems.  It  is  a  book  written  and  illustrated  by  a  prac- 
tical shop  man  for  practical  shop  men  who  are  too  busy  to  read  theories  and  want  facts. 
It  is  the  most  complete  all-round  book  of  its  kind  ever  published. .  384  pages. 
219  original  and  specially-made  illustrations.  Revised  and  Enlarged  Edition. 
Price $5.00 

"SHOP  KINKS."    By  Robert  Grimshaw. 

A  book  of  400  pages  and  222  illustrations,  being  entirely  different  from  any  other 
book  on  machine-shop  practice.  Departing  from  conventional  style,  the  author 
avoids  universal  or  common  shop  usage  and  limits  his  work  to  showing  special  ways 
of  doing  things  better,  more  cheaply  and  more  rapidly  than  usual.  As  a  result  the 
advanced  methods  of  representative  establishments  of  the  world  are  placed  at  the 
disposal  of  the  reader.  This  book  shows  the  proprietor  where  large  savings  are  possible, 
and  how  products  may  be  improved.  To  the  employee  it  holds  out  suggestions  that, 
properly  applied,  will  hasten  his  advancement.  No  shop  can  afford  to  be  without  it. 
It  bristles  with  valuable  wrinkles  and  helpful  suggestions.  It  will  benefit  all.  from 
apprentice  to  proprietor.     5th  edition.     Price $3.00 

THREADS  AND  THREAD-CUTTING.     By  Colvin  and  Stabel. 

This  clears  up  many  of  the  mysteries  of  thread-cutting,  such  as  double  and  triple 
threads,  internal  threads,  catching  threads,  use  of  hobs,  etc.  Contains  a  lot  of  useful 
hints  and  several  tables.    4th  edition.    Price  ._ 35  €@nt§ 

27 


CATALOGUE   OF  GOOD,  PRACTICAL  BOOKS 


THE  WHOLE  FIELD  OF  MECHANICAL  MOVEMENTS 
COVERED  BY  MR.  HISCOX'S  TWO  BOOKS 


We  publish  two  books  by  Gardner  D.  Hiscox  that  will  keep  you  from  "inventing'*  things 
that  have  been  done  before,  and  suggest  ways  of  doing  things  that  you  have  not  thought  of 
before.  Many  a  man  spends  time  and  money,  pondering  over  some  mechanical  problem, 
only  to  learn,  after  he  has  solved  the  problem,  that  the  same  thing  has  been  accomplished 
and  put  in  practice  by  others  long  before.  Time  and  money  spent  in  an  effort  to  accom- 
plish what  has  already  been  accomplished  are  time  and  money  LOST.  The  whole  field 
of  mechanics,  every  known  mechanical  movement,  and  practically  every  device  is  covered 
by  these  two  books.  If  the  thing  you  want  has  been  invented,  it  is  illustrated  in  them.  If 
it  hasn't  been  invented,  then  you'll  find  in  them  the  nearest  things  to  what  you  want,  some 
movements  or  devices  that  will  apply  in  your  case,  perhaps;  or  which  will  give  you  a  key 
from  which  to  work.  No  book  or  set  of  books  ever  published  is  of  more  real  value  to  the 
Inventor,  Draftsman,  or  practical  Mechanic  than  the  two  volumes  described  below. 

MECHANICAL  MOVEMENTS,  POWERS,  AND  DEVICES.    By  Gardner  D. 

Hiscox. 

This  is  a  collection  of  1,890  engravings  of  different  mechanical  motions  and  appliances, 
accompanied  by  appropriate  text,  making  it  a  book  of  great  value  to  the  inventor, 
the  draftsman,  and  to  all  readers  with  mechanical  tastes.  The  book  is  divided  into 
eighteen  sections  or  chapters,  in  which  the  subject-matter  is  classified  under  the  follow- 
ing heads:  Mechanical  Powers;  Transmission  of  Power;  Measurement  of  Power; 
Steam  Power;  Air  Power  Appliances;  Electric  Power  and  Construction;  Navigation 
and  Roads;  Gearing;  Motion  and  Devices;  Controlling  Motion;  Horological; 
Mining;  Mill  and  Factory  Appliances;  Construction  and  Devices;  Drafting  Devices; 
Miscellaneous  Devices,  etc.     15th  edition  enlarged.    400  octavo  pages.    Price  .  $4.00 

MECHANICAL  APPLIANCES,  MECHANICAL  MOVEMENTS  AND  NOVEL- 
TIES OF  CONSTRUCTION.    By  Gardner  D.  Hiscox. 

This  is  a  supplementary  volume  to  the  one  upon  mechanical  movements.  Unlike  the 
first  volume,  which  is  more  elementary  in  character,  this  volume  contains  illustrations 
and  descriptions  of  many  combinations  of  motions  and  of  mechanical  devices  and 
appliances  found  in  different  lines  of  machinery,  each  device  being  shown  by  a  line 
drawing  with  a  description  showing  its  working  parts  and  the  method  of  operation. 
From  the  multitude  of  devices  described  and  illustrated  might  be  mentioned,  in 
passing,  such  items  as  conveyors  and  elevators,  Prony  brakes,  thermometers,  various 
types  of  boilers,  solar  engines,  oil-fuel  burners,  condensers,  evaporators,  Corliss  and 
other  valve  gears,  governors,  gas  engines,  water  motors  of  various  descriptions,  air- 
ships, motors  and  dynamos,  automobile  and  motor  bicycles,  railway  lock  signals, 
car  couplers,  link  and  gear  motions,  ball  bearings,  breech  block  mechanism  for  heavy 
guns,  and  a  large  accumulation  of  others  of  equal  importance.  1,000  specially  made 
engravings.     396  octavo  pages.    4th  Edition  enlarged.     Price $4.00 

SHOP  PRACTICE  FOR  HOME  MECHANICS.   By  Raymond  Francis  Yates. 

A  thoroughly  practical  and  helpful  treatment  prepared  especially  for  those  who  have 
had  little  or  no  experience  in  shop  work.  The  introduction  is  given  over  to  an  ele- 
mentary explanation  of  the  fundamentals  of  mechanical  science.  This  is  followed 
by  several  chapters  on  the  use  of  small  tools  and  mechanical  measuring  instruments. 
Elementary  and  more  advanced  lathe  work  is  treated  in  detail  and  directions  given 
for  the  construction  of  a  number  of  useful  shop  appliances.  Drilling  and  reaming, 
heat  treatment  of  tool  steel,  special  lathe  operations,  pattern  making,  grinding,  and 
grinding  operations,  home  foundry  work,  etc.,  make  up  the  rest  of  the  volume.  The 
book  omits  nothing  that  will  be  of  use  to  those  who  use  tools  or  to  those  who  wish 
to  learn  the  use  of  tools  The  great  number  of  clear  engravings  (over  300)  add 
tremendously  to  the  text  matter  and  to  the  value  of  the  volume  as  a  visual  instructor. 
Octavo,  320  pages,    309  engravings.     Price     ♦     ,,,,,,,...    $3.00 


28 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 


MACHINE-SHOP  TOOLS  AND  SHOP  PRACTICE.    By  W.  H.  Vandervoort. 

A  work  of  552  pages  and  672  illustrations,  describing  in  every  detail  the  construction, 
operation,  and  manipulation  of  both  hand  and  machine  tools.  Includes  chapters 
on  filing,  fitting,  and  scraping  surfaces ;  on  drills,  reamers,  taps,  and  dies ;  the  lathe 
and  its  tools;  planers,  shapers,  and  their  tools;  milling  machines  and  cutters;  gear 
cutters  and  gear  cutting;  drilling  machines  and  drill  work;  grinding  machines  and 
their  work;  hardening  and  tempering;  gearing,  belting,  and  transmission  machinery; 
useful  data  and  tables.     7th  Edition.      552  pages.    672  illustrations.      Price  $4.50 

COMPLETE  PRACTICAL  MACHINIST.    By  Joshua  Rose. 

The  new,  twentieth  revised  and  enlarged  edition  is  now  ready.  This  is  one  of  the 
best-known  books  on  machine-shop  work,  and  written  for  the  practical  workman 
in  the  language  of  the  workshop.  It  gives  full,  practical  instructions  on  the  use  of 
all  kinds  of  metal-working  tools,  both  hand  and  machine,  and  tells  how  the  work 
should  be  properly  done.  It  covers  lathe  work,  vise  work,  drills  and  drilling,  taps 
and  dies,  hardening  and  tempering,  the  making  and  use  of  tools,  tool  grinding,  mark- 
ing out  work,  machine  tools,  etc.  No  machinist's  library  is  complete  without  this 
TOlume.     20th  Edition.     547  pages.  432  illustrations.     Price     ....     $3.00 

HENLEY'S  ENCYCLOPEDIA  OF  PRACTICAL  ENGINEERING  AND  ALLIED 
TRADES.    Edited  by  Joseph  G.  Horner,  A.M.LMech.E. 

This  book  covers  the  entire  practice  of  Civil  and  Mechanical  Engineering.  Tho 
best  known  experts  in  all  branches  of  engineering  have  contributed  to  these  volumes. 
The  Cyclopedia  is  admirably  well  adapted  to  the  needs  of  the  beginner  and  the  self- 
taught  practical  man,  as  well  as  the  mechanical  engineer,  designer,  draftsman,  shop 
superintendent,  foreman  and  machinist. 

It  is  a  moderm  treatise  in  five  volumes.  Handsomely  bound  in  half  morocco,  each 
volume  containing  nearly  500  pages,  with  thousands  of  illustrations,  including  dia- 
grammatic and  sectional  drawings  with  full  explanatory  details.  Five  large  volumes. 
Price $30.00 

MODEL  MAKING  Including  Workshop  Practice,  Design  and  Construction  of 
Models.  Edited  by  Raymond  F.  Yates.  Editor  of  "Everyday  Engineering 
Magazine." 

This  book  will  help  you  to  become  a  better  mechanic.  It  is  full  of  suggestions  for  those 
who  like  to  make  things,  amateur  and  professional  alike.  It  has  been  prepared  es- 
pecially for  men  with  mechanical  hobbies.  Some  may  be  engineers,  machinists,  jew- 
elers, pattern  makers,  office  clerks  or  bank  presidents.  Men  from  various  walks  of 
life  have  a  peculiar  interest  in  model  engineering.  Model  Making  will  be  a  help  and 
an  inspiration  to  such  men.  It  tells  them  "how-to-do"  and  "how-to-make"  things 
in  simple,  understandable  terms.  Not  only  this,  it  is  full  of  good,  clear  working 
drawings  and  photographs  of  the  models  and  apparatus  described.  Each  model  has 
been  constructed  and  actually  works  if  it  is  made  according  to  directions.  379  pages. 
300  illustrations.     Price , $3.00 

ABRASIVES  AND  ABRASIVE  WHEELS.    By  Fred  B.  Jacobs. 

A  new  book  for  everyone  interested  in  abrasives  or  grinding.  A  careful  reading  of 
the  book  will  not  only  make  mechanics  better  able  to  use  abrasives  intelligently,  but 
it  will  also  tell  the  shop  superintendent  of  many  short  cuts  and  efficiency-increasing 
kinks.  The  economic  advantages  in  using  large  grinding  wheels  are  fully  explained, 
together  with  many  other  things  that  will  tend  to  give  the  superintendent  or  workman 
a  keen  insight  into  abrasive  engineering.  340  pages.  174  illustrations.  This  is  an 
indispensable  book  for  every  machinist.     Price $3.00 

HOME  MECHANIC'S  WORKSHOP  COMPANION.  By  Andrew  Jackson,  Jr. 

This  treatise  includes  a  compilation  of  useful  suggestions  that  cannot  fail  to  interest 
the  handy  man,  and  while  it  is  not  intended  for  mechanical  experts  or  scientists,  it  will 
prove  to  be  a  veritable  store  of  information  for  anyone  who  desires  to  rig  up  a  small 
shop  where  odd  jobs  can  be  carried  on.     Price 75  cents 

29 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 
MARINE  ENGINEERING 

THE  NAVAL  ARCHITECT'S  AND   SHIPBUILDER'S  POCKETBOOK.     Of 

Formulae,  Rules,  and  Tables  and  Marine  Engineer's  and  Surveyor's  Handy 

Book  of  Reference.     By  Clement  Mackrow  and  Lloyd  Woollard. 

The  twelfth  revised  and  enlarged  edition  of  this  most  comprehensive  work  has  just 
been  issued.  It  is  absolutely  indispensable  to  all  engaged  in  the  Shipbuilding  Industry, 
as  it  condenses  into  a  compact  form  all  data  and  formulaeithat  are  ordinarily  required. 
The  book  is  completely  up  to  date,  including  among  other  subjects  a  section  on 
Aeronautics.     760  pages,  limp  leather  binding.     Price $6.00 

MARINE  ENGINES  AND  BOILERS— THEIR  DESIGN  AND  CONSTRUC- 
TION. THE  STANDARD  BOOK.  By_Dn.  G.  Bauer,  Leslie  S.  Robertson 
and  S.  Bryan  Donkin. 

In  the  words  of  Dr.  Bauer,  the  present  work  owes  its  origin  to  an  oft  felt  want  of  a 
condensed  treatise  embodying  the  theoretical  and  practical  rules  used  in  designing 
marine  engines  and  boilers.  The  fact  that  the  original  German  work  was  written  by 
the  chief  engineer  of  the  famous  Vulcan  Works,  Stettin,  is  in  itself  a  guarantee  that 
this  book  is  in  all  respects  thoroughly  up-to-date,  and  that  it  embodies  all  the  in- 
formation which  is  necessary  for  the  design  and  construction  of  the  highest  types  of 
marine  engines  and  boilers.  It  may  be  said  that  the  motive  power  which  Dr.  Bauer 
has  placed  in  the  fast  German  liners  that  have  been  turned  out  of  late  years  from  the 
Stettin  Works  represent  the  very  best  practice  in  marine  engineering  of  the  present 
day.  The  work  is  clearly  written,  thoroughly  systematic,  theoretically  sound;  while 
the  character  of  the  plans,  drawings,  tables,  and  statistics  is  without  reproach.  The 
illustrations  are  careful  reproductions  from  actual  working  drawings,  with  some  well- 
executed  photographic  views  of  completed  engines  and  boilers.  Fifth  impression. 
,744  pages.     550  illustrations,  and  numerous  tables.     Cloth.    Price  .     .     .     $10.00 

MANUAL  TRAINING 

«■—  — !■■■      r»    i...m      ^        i  ^^^wt 

ECONOMICS  OF  MANUAL  TRAINING.    By  Louis  Routllion. 

The  only  book  published  that  gives  just  the  information  needed  by  all  interested  in 
Manual  Training,  regarding  Buildings,  Equipment,  and  Supplies.  Shows  exactly 
what  is  needed  for  all  grades  of  the  work  from  the  Kindergarten  to  the  High  and 
Normal  School.  Gives  itemized  lists  of  everything  used  in  Manual  Training  Work 
and  tells  just  what  it  ought  to  cost.  Also  shows  where  to  buy  supplies,  etc.  Contains 
1 174  pages,  and  is  fully  illustrated.     2d  edition.    Price $2.00 

MOTOR  BOATS 

MOTOR  BOATS  AND  BOAT  MOTORS.  By  Victor  W.  Page  and  A.  C.  Leitch. 

All  who  are  interested  in  motor  boats,  either  as  owners,  builders  or  repairmen,  will 
find  this  latest  work  a  most  comprehensive  treatise  on  the  design,  construction,  opera- 
tion and  repair  of  motor  boats  and  their  power  plants.  It  is  really  two  complete 
books  in  one  cover  as  it  consists  of  two  parts,  each  complete  in  itself.  Part  One  deals 
with  The  Hull  and  Its  Fittings,  Part  Two  considers  The  Power  Plant  and  Its 
Auxiliaries.  A  valuable  feature  of  this  book  is  the  complete  set  of  dimensioned 
working  drawings  detailing  the  construction  of  five  different  types  of  boats  ranging 
from  a  16-foot  shallow  draft,  tunnel  stern  general  utility  craft  to  a  25-foot  cabin 
cruiser.  These  plans  are  by  A.  C.  Leitch,  a  practical  boat  builder  and  expert  naval 
architect,  and  are  complete  in  every  particular.  Full  instructions  are  given  for  the 
selection  of  a  power  plant  and  its  installation  in  the  hull.  Valuable  advice  is  included 
on  boat  and  engine  operation  and  latest  designs  of  motors  are  described  and  illustrated. 
The  instructions  for  overhauling  boat  and  engine  are  worth  many  times  the  small 
cost  of  the  book.  It  is  a  comprehensive  work  of  reference  for  all  interested  in  motor 
boating  in  any  of  its  phases.  Octavo.  Cloth.  372  illustrations.  524  pages. 
Price $4.00. 

3° 


CATALOGUE   OF  GOOD,  PRACTICAL  BOOKS 


MOTORCYCLES 

MOTORCYCLES  AND  SIDE  CARS,  THEIR  CONSTRUCTION,  MANAGE- 
MENT AND  REPAIR.    By  Victor  W.  Page,  M.E. 

The  only  complete  work  published  for  the  motorcyclist  and  repairman.  Describes 
fully  all  leading  types  of  machines,  their  design,  construction,  maintenance,  operation 
and  repair.  This  treatise  outlines  fully  the  operation  of  two-  and  four-cycle  power 
plants  and  all  ignition,  carburetion  and  lubrication  systems  in  detail.  Describes  all 
representative  types  of  free  engine  clutches,  variable  speed  gears  and  power  trans* 
mission  systems.  Gives  complete  instructions  for  operating  and  repairing  all  types. 
Considers  fully  electric  self-starting  and  lighting  systems,  all  types  of  spring  frames 
and  spring  forks  and  shows  leading  control  methods.  For  those  desiring  technical 
information  a  complete  series  of  tables  and  many  formulae  to  assist  in  designing  are 
included.  The  work  tells  how  to  figure  power  needed  to  climb  grades,  overcome  air 
resistance  and  attain  high  speeds.  It  shows  how  to  select  gear  ratios  for  various 
weights  and  powers,  how  to  figure  braking  efficiency  required,  gives  sizes  of  belts  and 
chains  to  transmit  power  safely,  and  shows  how  to  design  sprockets,  belt  pulleys,  etc. 
This  work  also  includes  complete  formulas  for  figuring  horse-power,  shows  how  dyna- 
mometer tests  are  made,  defines  relative  efficiency  of  air-  and  water-cooled  engines,  plain 
and  anti-friction  bearings  and  many  other  data  of  a  practical,  helpful,  engineering 
nature.  Kemember  that  you  get  this  information  in  addition  to  the  practical  de- 
scription and  instructions  which  alone  are  worth  several  times  the  price  of  the  book. 
2nd  Edition  Revised  and  Enlarged.  693  pages.  371  specially  made  illustrations. 
Cloth.    Price $3.00 

WHAT  IS  SAID  OF  THIS  BOOK: 

"  Here  is  a  book  that  should  be  in  the  cycle  repairer's  kit." — American  Blacksmith. 
"  The  best  way  for  any  rider  to  thoroughly  understand  his  machine,  is  to  get  a  copy 
of  this  book;  it  is  worth  many  times  its  price." — Pacific  Motorcyclist. 


PATTERN  MAKING 

PRACTICAL  PATTERN  MAKING.    By  F.  W.  Barrows. 

This  book,  now  in  its  second  edition,  is  a  comprehensive  and  entirely  practical  treatise 
on  the  subject  of  pattern  making,  illustrating  pattern  work  in  both  wood  and  metal, 
and  with  definite  instructions  on  the  use  of  plaster  of  Paris  in  the  trade.  It  gives 
specific  and  detailed  descriptions  of  the  materials  used  by  pattern  makers  and  de- 
scribes the  tools,  both  those  for  the  bench  and  the  more  interesting  machine  tools; 
having  complete  chapters  on  the  Lathe,  the  Circular  Saw,  and  the  Band  Saw.  It  gives 
many  examples  of  pattern  work,  each  one  fully  illustrated  and  explained  with  much 
detail.  These  examples,  in  their  great  variety,  offer  much  that  will  be  found  ot 
interest  to  all  pattern  makers,  and  especially  to  the  younger  ones,  who  are  seeking 
information  on  the  more  advanced  branches  of  their  trade. 

In  this  second  edition  of  the  work  will  be  found  much  that  is  new,  even  to  those  who 
have  long  practiced  this  exacting  trade.  In  the  description  of  patterns  as  adapted 
to  the  Moulding  Machine  many  difficulties  which  have  long  prevented  the  rapid  and 
economical  production  of  castings  are  overcome;  and  this  great,  new  branch  of  the 
trade  is  given  much  space.  Stripping  plate  and  stool  plate  work  and  the  less  expen- 
sive vibrator,  or  rapping  plate  work,  are  all  explained  in  detail. 

Plain,  everyday  rules  for  lessening  the  cost  of  patterns,  with  a  complete  system  of 
cost  keeping,  a  detailed  method  of  marking,  applicable  to  all  branches  of  the  trade, 
with  complete  information  showing  what  the  pattern  is,  its  specific  title,  its  cost, 
date  of  production,  material  of  which  it  is  made,  the  number  of  pieces  and  core- 
boxes,  and  its  location  in  the  pattern  safe,  all  condensed  into  a  most  complete  card 
record,  with  cross  index. 

The  book  closes  with  an  original  and  practical  method  for  the  inventory  and  valua- 
tion of  patterns.  2nd  Edition.  Containing  nearly  350  pages  and  170  illustra- 
tions.   Price $2.50 


3i 


CATALOGUE   OF  GOOD,  PRACTICAL  BOOKS 


PERFUMERY 

PERFUMES  AND  COSMETICS,  THEIR  PREPARATION  AND  MANUFAC- 
TURE.   By  G.  W.  Askinson,  Perfumer. 

A  comprehensive  treatise,  in  which  there  has  been  nothing  omitted  that  could  be  of 
value  to  the  perfumer  or  manufacturer  of  toilet  preparations.  Complete  directions 
for  making  handkerchief  perfumes,  smelling-salts,  sachets,  fumigating  pastilles; 
preparations  for  the  care  of  the  skin,  the  mouth,  the  hair,  cosmetics,  hair  dyes  and 
other  toilet  articles  are  given,  also  a  detailed  description  of  aromatic  substances ;  their 
nature,  tests  of  purity,  and  wholesale  manufacture,  including  a  chapter  on  synthetic 
products,  with  formulas  for  their  use.  A  book  of  general,  as  well  as  professional  in- 
terest, meeting  the  wants  not  only  of  the  druggist  and  perfume  manufacturer,  but 
also  of  the  general  public.  Fourth  Edition  much  enlarged  and  brought  up-to-date. 
Nearly   400  pages,   illustrated.     Price $5.00 

WHAT  IS  SAID  OF  THIS  BOOK: 
•'  The  most  satisfactory  work  on  the  subject  of  Perfumery  that  we  have  ever  seen. 
•'  We  feel  safe  in  saying  that  here  is  a  book  on  Perfumery  that  will  not  disappoint  you, 
for  it  has  practical  and  excellent  formulae  that  are  within  your,  ability  to  prepare 
readily. 

"  We  recommend  the  volume  as  worthy  of  confidence,  and  say  that  no  purchaser  will  be 
disappointed  in  securing  from  its  pages  good  value  for  its  cost,  and  a  large  dividend 
on  the  same,  even  if  he  should  use  but  one  per  cent  of  its  working  formulae.  There 
is  money  in  it  for  every  user  of  its  information." — Pharmaceutical  Record. 


PLUMBING 

MECHANICAL  DRAWING  FOR  PLUMBERS.    By  R.  M.  Starbuck. 

A  concise,  comprehensive  and  practical  treatise  on  the  subject  of  mechanical  drawing 
in  its  various  modern  applications  to  the  work  of  all  who  are  in  any  way  connected 
with  the  plumbing  trade.  Nothing  will  so  help  the  plumber  in  estimating  and  in 
explaining  work  to  customers  and  workmen  as  a  knowledge  of  drawing,  and  to  the 
workman  it  is  of  inestimable  value  if  he  is  to  rise  above  his  position  to  positions  of 
greater  responsibility.  Among  the  chapters  contained  are:  1.  Value  to  plumber  of 
knowledge  of  drawing ;  tools  required  and  their  use ;  common  views  needed  in  mechan- 
ical drawing.  2.  Perspective  versus  mechanical  drawing  in  showing  plumbing  con- 
struction. 3.  Correct  and  incorrect  methods  in  plumbing  drawing;  plan  and  elevation 
explained.  4.  Floor  and  cellar  plans  and  elevation;  scale  drawings;  use  of  triangles. 
5.  Use  of  triangles;  drawing  of  fittings,  traps,  etc.  6.  Drawing  plumbing  elevations 
and  fittings.  7.  Instructions  in  drawing  plumbing  elevations.  8.  The  drawing  of 
plumbing  fixtures;  scale  drawings.  9.  Drawings  of  fixtures  and  fittings.  10.  Inking 
of  drawings.  11.  Shading  of  drawings.  12.  Shading  of  drawings.  13.  Sectional 
drawings;  drawing  of  threads.  14.  Plumbing  elevations  from  architect's  plan.  15.  Ele- 
vations of  separate  parts  of  the  plumbing  system.  16.  Elevations  from  the  architect's 
plans.  17.  Drawings  of  detail  plumbing  connections.  18.  Architect's  plans  and  plumb- 
ing elevations  of  residence.  19.  Plumbing  elevations  of  residence  (continued) ;  plumb- 
ing plans  for  cottage.  20.  Plumbing  elevations;  roof  connections.  21.  Plans  and 
plumbing  elevations  for  six-flat  building.  22.  Drawing  of  various  parts  of  the  plumb- 
ing system;  use  of  scales.  23.  Use  of  architect's  scales.  24.  Special  features  in  the 
illustrations  of  country  plumbing.  25.  Drawing  of  wrought-iron  piping,  valves,  radia- 
tors, coils,  etc.  26.  Drawing  of  piping  to  illustrate  heating  systems.  150  illustrations. 
Price $2.00 


32 


CATALOGUE  OF  GOOD,  PRACTICAL  BOOKS 


MODERN  PLUMBING  ILLUSTRATED.    By  R.  M.  Starbuck. 

This  book  represents  the  highest  standard  of  plumbing  work.  It  has  been  adopted 
and  used  as  a  reference  book  by  the  United  States  Government,  in  its  sanitary  work  in 
Cuba,  Porto  Rico,  and  the  Philippines,  and  by  the  principal  Boards  of  Health  of  the 
United  States  and  Canada. 

It  gives  connections,  sizes  and  working  data  for  all  fixtures  and  groups  of  fixtures.  It 
is  helpful  to  the  master  plumber  in  demonstrating  to  his  customers  and  in  figuring 
work.  It  gives  the  mechanic  and  student  quick  and  easy  access  to  the  best  modern 
plumbing  practice.  Suggestions  for  estimating  plumbing  construction  are  contained 
in  its  pages.  This  book  represents,  in  a  word,  the  latest  and  best  up-to-date  practice 
and  should  be  in  the  hands  of  every  architect,  sanitary  engineer  and  plumber  who 
wishes  to  keep  himself  up  to  the  minute  on  this  important  feature  of  construction. 
Contains  following  chapters,  each  illustrated  with  a  full-page  plate:  Kitchen  sink, 
laundry  tubs,  vegetable  wash  sink;  lavatories,  pantry  sinks,  contents  of  marble  slabs; 
bath  tub,  foot  and  sitz  bath,  shower  bath;  water  closets,  venting  of  water  closets;  low* 
down  water  closets,  water  closets  operated  by  flush  valves,  water  closet  range ;  slop  sink, 
urinals,  the  bidet;  hotel  and  restaurant  sink,  grease  trap;  refrigerators,  safe  wastes,  laun- 
dry waste,  fines  of  refrigerators,  bar  sinks,  soda  fountain  sinks ;  horse  stall,  frost-proof 
water  closets;  connections  for  S  traps,  venting;  connections  for  drum  traps;  soil  pipe 
connections;  supporting  of  soil  pipe;  main  trap  and  fresh  air  inlet;  floor  drains  and 
cellar  drains,  subsoil  drainage;  water  closets  and  floor  connections;  local  venting; 
connections  for  bath  rooms;  connections  for  bath  rooms,  continued;  connections  for 
bath  rooms,  continued;  connections  for  bath  rooms,  continued;  examples  of  poor 
practice;  roughing  work  ready  for  test;  testing  of  plumbing  system;  method  of  con- 
tinuous venting;  continuous  venting  for  two-floor  work;  continuous  venting  for  two 
lines  of  fixtures  on  three  or  more  floors;  continuous  venting  of  water  closets;  plumb- 
ing for  cottage  house;  construction  for  cellar  piping;  plumbing  for  residence,  use  of 
special  fittings;  plumbing  for  two-flat  house;  plumbing  for  apartment  building,  plumb- 
ing for  double  apartment  building;  plumbing  for  office  building;  plumbing  for  public 
toilet  rooms;  plumbing  for  public  toilet  rooms,  continued;  plumbing  for  bath  estab- 
lishment; plumbing  for  engine  house,  factory]  plumbing;  automatic  flushing .  for 
schools,  factories,  etc.;  use  of  flushing  valves;  urinals  for  public  toilet  rooms;  the 
Durham  system,  the  destruction  of  pipes  by  electrolysis;  construction  of  work  without 
use  of  lead;  automatic  sewage  lift;  automatic  sump  tank;  country  plumbing;  construc- 
tion of  cesspools ;  septic  tank  and  automatic  sewage  siphon ;  country  plumbing ;  water 
supply  for  country  house;  thawing  of  water  mains  and  service  by  electricity;  double 
boilers;  hot  water  supply  of  large  buildings;  automatic  control  of  hot  water  tank;  sug- 
gestion for  estimating  plumbing  construction.  407  octavo  pages,  fully  illustrated  by  58 
full-page  engravings.    Third,  revised  and  enlarged  edition  just  issued.    Price  .  $5.00 

STANDARD  PRACTICAL  PLUMBING.    By  R.  M. '  Starbuck. 

A  complete  practical  treatise  of  450  pages  covering  the  subject  of  Modern  Plumbing 
in  all  its  branches,  a  large  amount  of  space  being  devoted  to  a  very  complete  and 
practical  treatment  of  the  subject  of  Hot  Water  Supply  and  Circulation  and  Range 
Boiler  "Work.  Its  thirty  chapters  include  about  every  phase  of  the  subject  one  can 
think  of,  making  it  an  indispensable  work  to  the  master  plumber,  the  journeyman 
plumber,  and  the  apprentice  plumber,  containing  chapters  on:  the  plumber's  tools; 
wiping  solder;  composition  and  use;  joint  wiping;  lead  work;  traps;  siphonage  of 
traps;  venting;  continuous  venting;  house  sewer  and  sewer  connections;  house  drain; 
soil  piping,  roughing;  main  trap  and  fresh  air  inlet;  floor,  yard,  cellar  drains,  rain 
leaders,  etc.;  fixture  wastes;  water  closets;  ventilation;  improved  plumbing  connec- 
tions; residence  plumbing;  plumbing  for  hotels,  schools,  factories,  stables,  etc.; 
modern  country  plumbing;  filtration  of  sewage  and  water  supply;  hot  and  cold 
supply;  range  boilers;  circulation;  circulating  pipes;  range  boiler  problems;  hot 
water  for  large  buildings;  water  lift  and  its  use;  multiple  connections  for  hot  water 
boilers;  heating  of  radiation  by  supply  system;  theory  for  the  plumber;  drawing  for 
the  plumber.    Fully  illustrated  by  347  engravings,    price  .     ,    ,    ,_,    ,    .     $3,50 


33 


CATALOGUE   OF   GOOD,   PRACTICAL  BOOKS 


RECIPE  BOOK 

HENLEY'S  TWENTIETH  CENTURY  BOOK  OF  RECIPES,  FORMULAS  AND 
PROCESSES.    Edited  by  Gardner  D.  Hiscox. 

The  most  valuable  Techno-chemical  Formula'Book  published,  including  over  10,000 
selected  scientific,  chemical,  technological,  and  practical  recipes  and  processes. 
This  is  the  most  complete  Book  of  Formulas  ever  published,  giving  thousands  of 
recipes  for  the  manufacture  of  valuable  articles  for  everyday  use.  Hints,  Helps, 
Practical  Ideas,  and  Secret  Processes  are  revealed  within  its  pages.  It  covers  every 
branch  of  the  useful  arts  and  tells  thousands  of  ways  of  making  money,  and  is  just  the 
book  everyone  should  have  at  his  command. 

Modern  in  its  treatment  of  every  subject  that  properly  falls  within  its  scope,  the  book 
may  truthfully  be  said  to  present  the  very  latest  formulas  to  be  found  in  the  arts  and 
industries,  and  to  retain  those  processes  which  long  experience  has  proven  worthy  of  a 
permanent  record.  To  present  here  even  a  limited  number  of  the  subjects  which  find 
a  place  in  this  valuable  work  would  be  difficult.  Suffice  to  say  that  in  its  pages  will 
be  found  matter  of  intense  interest  and  immeasurably  practical  value  to  the  scientific 
amateur  and  to  him  who  wishes  to  obtain  a  knowledge  of  the  many  processes  used  in 
the  arts,  trades  and  manufacture,  a  knowledge  which  will  render  his  pursuits  more 
instructive  and  remunerative.  Serving  as  a  reference  book  to  the  small  and  large 
manufacturer  and  supplying  intelligent  seekers  with  the  information  necessary  to 
conduct  a  process,  the  work  will  be  found  of  inestimable  worth  to  the  Metallurgist,  the 
Photographer,  the  Perfumer,  the  Painter,  the  Manufacturer  of  Glues,  Pastes,  Cements, 
a*id  Mucilages,  the  Compounder  of  Alloys,  the  Cook,  the  Physician,  the  Druggist,  the 
Electrician,  the  Brewer,  the  Engineer,  the  Poundryman,  the  Machinist,  the  Potter,  the 
Tanner,  the  Confectioner,  the  Chiropodist,  the  Manicure,  the  Manufacturer  of  Chem- 
ical Novelties  and  Toilet  Preparations,  the  Dyer,  the  Electroplater,  the  Enameler,  the 
Engraver,  the  Provisioner,  the  Glass  Worker,  the  Goldbeater,  the  Watchmaker,  the 
Jeweler,  the  Hat  Maker,  the  Ink  Manufacturer,  the  Optician,  the  Farmer,  the  Dairy- 
man, the  Paper  Maker,  the  Wood  and  Metal  Worker,  the  Chandler  and  Soap  Maker, 
the  Veterinary  Surgeon,  and  the  Technologistjn  general. 

A  mine  of  information,  and  up-to-date  in  every  respect.  A  book  which  will  prove  of 
value  to  EVERYONE,  as  it  covers  every  branch  of  the  Useful  Arts.  Every  home 
needs  this  book;  every  office,  every  factory,  every  store,  every  public  and  private  en- 
terprise—  EVERYWHERE  —  shouldj  have  a  copy.  800  pages.  Cloth  Bound. 
Price $4.00 

WHAT   IS   SAID   OF   THIS   BOOK: 

"Your  Twentieth  Century  Book  of  Recipes,  Formulas,  and  Processes  duly  received. 
I  am  glad  to  have  a  copy  of  it,  and  if  I  could  not  replace  it,  money  couldn't  buy  it„  It 
is  the  best  thing  of  the  sort  I  ever  saw."  (Signed)  M.  E.  Trxjx,  Sparta,  Wis. 
"There  are  few  persons  who  would  not  be  able  to  find  in  the  book  some  single  formula 
that  would  repay  several  times  the  cost  of  the  book." — Merchants'  Record  and  Show 
Window. 

"I  purchased  your  book  'Henley's  Twentieth  Century  Book  of  Recipes,  Formulas  and 
Processes'  about  a  year  ago  and  it  is  worth  its  weight  in  gold." — Wm.  H.  Murray, 
;  .Bennington,  Vt. 

''THE  BOOK  WORTH  THREE  HUNDRED  DOLLARS" 

"On  close  examination  of  your  'Twentieth  Century  Receipt  Book,'  I  find  it  to  be  a 
very  valuable  and  useful  book  with  the  very  best  of  practical  information  obtainable. 
The  price  of  the  book,  $4.00,  is  very  small  in  comparison  to  the  benefits  which  one  can 
obtain  from  it.  I  consider  the  book  worth  fully  three  hundred  dollars  to  anyone." 
— Dr.  A.  C.  Spetts,  New  York. 

"ONE  OF  THE  WORLD'S  MOST  USEFUL  BOOKS" 
"  Some  time  ago,  I  got  one  of  your  '  Twentieth  Century  Books  of  Formulas '  and  have 
made  my  living  from  it  ever  since.  I  am  alone  since  my  husband's  death  with  two 
small  children  to  care  for  and  am  trying  so  hard  to  support  them.  I  have  customers 
who  take  from  me  Toilet  Articles  I  put  up,  following  directions  given  in  the  book, 
and  I  have  found  every  one  of  them  to  be  fine." — Mrs.  J.  H.  McMaken,  West  Toledo, 
Ohio.    - 


34 


CATALOGUE   OF   GOOD,   PRACTICAL  BOOKS 

~— — ^ — *^— ^— — — — — -■— — ^ — "— ■ ~— *^ ■■ - — — *~ » — — — *~ ■— — ■ ■■ ~^ — — ^ ^— «■» 

'  mil  » 

RUBBER 

RUBBER  HAND  STAMPS  AND  THE  MANIPULATION  OF  INDIA  RUBBER. 

By  T.  O'Conok  Sloane. 

This  book  gives  full  details  on  all  points,  treating  in  a  concise  and  simple  manner  the 
elements  of  nearly  everything  it  is  necessary  to  understand  for  a  commencement  in 
any  branch  of  the  India  Rubber  Manufacture.  The  making  of  all  kinds  of  Rubber 
Hand  Stamps,  Small  Articles  of  India  Rubber,  U.  S.  Government  Composition,  Dating 
Hand  Stamps,  the  Manipulation  of  Sheet  Rubber,  Toy  Balloons,  India  Rubber  Solu- 
tions, Cements,  Blackings,  Renovating  Varnish,  and  Treatment  for  India  Rubber 
Shoes,  etc.;  the  Hektograph  Stamp  Inks,  and  Miscellaneous  Notes,  with  a  Short 
Account  of  the  Discovery,  Collection  and  Manufacture  of  India  Rubber,  are  set  forth 
in  a  manner  designed  to  be  readily  understood,  the  explanations  being  plain  and  simple. 
Including  a  chapter  on  Rubber  Tire  Making  and  Vulcanizing;  also  a  chapter  on  the 
uses  of  rubber  in  Surgery  and  Dentistry.  Third  revised  and  enlarged  edition.  175 
pages.    Illustrated .     $1.50 

SAWS 

SAW  FILING  AND  MANAGEMENT  OF  SAWS.     By  Robert  Grimshaw. 

A  practical  hand-book  on  filing,  gumming,  swaging,  hammering,  and  the  brazing  of 
band  saws,  the  speed,  work,  and  power  to  rim  circular  saws,  etc.  A  handy  book  for 
those  who  have  charge  of  saws,  or  for  those  mechanics  who  do  their  own  filing,  as  it  deals 
with  the  proper  shape  and  pitches  of  saw  teeth  of  all  kinds  and  gives  many  useful  hints 
and  rules  for  gumming,  setting,  and  filing,  and  is  a  practical  aid  to  those  who  use  saws 
for  any  purpose.  Complete  tables  of  proper  shape,  pitch,  and  saw  teeth  as  well  as 
sizes  and  number  of  teeth  of  various  saws  are  included.  Fourth  edition,  revised  and 
enlarged.     Illustrated.    Price $1.50 

SCREW   CUTTING 

THREADS  AND  THREAD-CUTTING.     By  Colvin  and  Stable. 

This  clears  up  many  of  the  mysteries  of  thread-cutting,  such  as  double  and  triple 
threads,  internal  threads,  catching  threads,  use  of  hobs,  etc.  Contains  a  lot  of  useful 
hints   and  several   tables.     Fourth   Edition.     Price       ......     35  cents 

STEAM  ENGINEERING 

MODERN   STEAM   ENGINEERING   IN  THEORY   AND    PRACTICE.    By 
Gardner  D.  Hiscox. 

This  is  a  complete  and  practical  work  issued  for  Stationary  Engineers  and  Firemen} 
dealing  with  the  care  and  management  of  boilers,  engines,  pumps,  superheated  steam, 
refrigerating  machinery,  dynamos,  motors,  elevators,  air  compressors,  and  all  other 
branches  with  which  the  modern  engineer  must  be  familiar.  Nearly  200  questions  with 
their  answers  on  steam  and  electrical  engineering,  likely  to  be  asked  by  the  Examin- 
ing Board,  are  included. 

Among  the  chapters  are:  Historical:  steam  and  its  properties;  appliances  for  the 
generation  of  steam;  types  of  boilers;  chimney  and  its  work;  heat  economy  of  the 
feed  water;  steam  pumps  and  their  work;  incrustation  and  its  work;  steam  above 
atmospheric  pressure ;  flow  of  steam  from  nozzles ;  superheated  steam  and  its  work ; 
adiabatic  expansion  of  steam ;  indicator  and  its  work ;  steam  engine  proportions ;  slide 
valve  engines  and  valve  motion;  Corliss  engine  and  its  valve  gear;  compound  engine 
and  its  theory;  triple  and  multiple  expansion  engine;  steam  turbine;  refrigeration; 
elevators  and  their  management;  cost  of  power;  steam  engine  troubles;  electric 
power  and  electric  plants.     487  pages.     405  engravings.     3d  Edition.  .     .     .     $3.50 


35 


CATALOGUE   OF  GOOD,  PRACTICAL  BOOKS 

AMERICAN  STATIONARY  ENGINEERING.    By  W.  E.  Crane. 

This  book  begins  at  the  boiler  room  and  takes  in  the  whole  power  plant.  A  plain 
talk  on  every-day  work  about  engines,  boilers,  and  their  accessories.  It  is  not  intended 
to  be  scientific  or  mathematical.  All  formulas  are  in  simple  form  so  that  anyone 
understanding  plain  arithmetic  can  readily  understand  any  of  them.  The  author 
has  made  this  the  most  practical  book  in  print ;  has  given  the  results  of  his  years  of 
experience,  and  has  included  about  all  that  has  to  do  with  an  engine  room  or  a  power 
plant.  You  are  not  left  to  guess  at  a  single  point.  You  are  shown  clearly  what  to 
expect  under  the  various  conditions ;  how  to  secure  the  best  results ;  ways  of  prevent- 
ing "shut  downs"  and  repairs;  in  short,  all  that  goes  to  make  up  the  requirements 
of  a  good  engineer,  capable  of  taking  charge  of  a  plant.  It's  plain  enough  for  practical 
men  and  yet  of  value  to  those  high  in  the  profession. 

A  partial  list  of  contents  is:  The  boiler  room,  cleaning  boilers,  firing,  feeding;  pumps; 
Inspection  and  repair;  chimneys,  sizes  and  cost;  piping;  mason  work;  foundations; 
testing  cement;  pile  driving;  engines,  slow  and  high  speed;  valves;  valve  setting; 
Corliss  engines,  setting  valves,  single  and  double  eccentric ;  air  pumps  and  condensers ; 
different  types  of  condensers;  water  needed;  lining  up;  pounds;  pins  not  square  in 
crosshead  or  crank;  engineers'  tools;  pistons  and  piston  rings;  bearing  metal;  hard- 
ened copper;  drip  pipes  from  cylinder  jackets;  belts,  how  made,  care  of;  oils;  greases: 
testing  lubricants;  rules  and  tables,  including  steam  tables;  areas  of  segments; 
squares  and  square  roots;  cubes  and  cube  root;  areas  and  circumferences  of  circles. 
Notes  on:  Brick  work;  explosions;  pumps;  pump  valves;  heaters,  economizers; 
safety  valves;  lap,  lead,  and  clearance.  Has  a  complete  examination  for  a  license, 
etc.,  etc.     Third  edition.    311  pages.     131  Illustrations.     Price.     .     .     .     $2.50 

ENGINE  RUNNER'S  CATECHISM."  By  Robert  Grimshaw. 

A  practical  treatise  for  the  stationary  engineer,  telling  how  to  erect,  adjust,  and  run 
the  principal  steam  engines  in  use  in  the  United  States.  Describing  the  principal 
features  of  various  special  and  well-known  makes  of  engines:  Temper  Cut-off,  Shipping 
and  Receiving  Foundations,  Erecting  and  Starting,  Valve  Setting,  Care  and  Use, 
Emergencies,  Erecting  and  Adjusting  Special  Engines. 

,The  questions  asked  throughout  the  catechism  are  plain  and  to  the  point,  and  the 
answers  are  given  in  such  simple  language  as  to  be  readily  understood  by  anyone.  All 
the  instructions  given  are  complete  and  up-to-date ;  and  they  are  written  in  a  popular 
style,  without  any  technicalities  or  mathematical  formulae.  The  work  is  of  a  handy 
size  for  the  pocket,  clearly  and  well  printed,  nicely  bound,  and  profusely  illustrated. 
To  young  engineers  this  catechism  will  be  of  great  value,  especially  to  those  who  may 
be  preparing  to  go  forward  to  be  examined  for  certificates  of  competency;  and  to 
engineers  generally  it  will  be  of  no  little  service,  as  they  will  find  in  this  volume  more 
really  practical  and  useful  information  than  is  to  be  found  anywhere  else  within  a  like 
compass.    387  pages.    Seventh  edition.    Price $2.00 

HORSE-POWER  CHART. 

Shows  the  horse-power  of  any  stationary  engine  without  calculation.  No  matter  what 
the  cylinder  diameter  of  stroke,  the  steam  pressure  of  cut-off,  the  revolutions,  or 
whether  condensing  or  non-condensing,  it's  all  there.  Easy  to  use,  accurate,  and 
saves  time  and  calculations.     Especially  useful  to  engineers  and  designers.     50  cents 

STEAM  ENGINE  CATECHISM.    By  Robert  Grimshaw. 

This  unique  volume  of  413  pages  is  not  only  a  catechism  on  the  question  and  answer 
principle,  but  it  Contains  formulas  and  worked-out  answers  for  all  the  Steam  problems 
that  appertain  to  the  operation  and  management  of  the  Steam  Engine.  Illustrations 
of  various  valves  and  valve  gear  with  their  principles  of  operation  are  given.  Thirty- 
foua  Tables  that  are  indispensable  to  every  engineer  and  fireman  that  wishes  to  be 
progressive  and  is  ambitious  to  become  master  of  his  calling  are  within  its  pages.  It  is 
a  most  valuable  instructor  in  the  service  of  Steam  Engineering.  Leading  engineers 
have  recommended  it  as  a  valuable  educator  for  the  beginneF  as  well  as  a  reference  book 
for  the  engineer.  It  is  thoroughly  indexed  for  every  detail.  Every  essential  question 
on  the  Steam  Engine  with  its  answer  is  contained  in  this  valuable  work.  Sixteenth 
edition    Price $2.00 


36 


CATALOGUE   OF   GOOD,  PRACTICAL  BOOKS 


STEAM  ENGINEER'S  ARITHMETIC.    By  Golvin-Cheney. 

A  practical  pocket-book  for  the  steam  engineer.  Shows  how  to  work  the  problems  of 
the  engine  room  and  shows  "why."  Tells  how  to  figure  horse-power  of  engines  and 
boilers;  area  of  boilers;  has  tables  of  areas  and  circumferences;  steam  tables;  has  a 
dictionary  of  engineering  terms.  Puts  you  on  to  all  of  the  little  kinks  in  figuring  what- 
ever there  is  to  figure  around  a  power  plant.  Tells  you  about  the  heat  unit;  absolute 
zero:  adiabatic  expansion;  duty  of  engines;  factor  of  safety;  and  a  thousand  and  one 
other  things;  and  everything  is  plain  and  simple — not  the  hardest  way  to  figure,  but 
the  easiest.     Second  Edition 75  cents 

STEAM  ENGINE  TROUBLES.    By  H.  Hamkens. 

It  is  safe  to  say  that  no  book  has  ever  been  published  which  gives  the  practical  en- 
gineer such  valuable  and  comprehensive  information  on  steam  engine  design  and 
troubles. 

Not  only  does  it  describe  the  troubles  the  principal  parts  of  steam  engines  are  subject 
to;  it  contrasts  good  design  with  bad,  points  out  the  most  suitable  material  for  certain 
parts,  and  the  most  approved  construction  of  the  same;  it  gives  directions  for  correct- 
ing existing  evils  by  following  which  breakdowns  and  costly  accidents  can  be  avoided. 
Just  look  into  the  nature  of  the  information  this  book  gives  on  the  following  sub- 
jects. There  are  descriptions  of  cylinders,  valves,  pistons,  frames,  pillow  blocks  and 
other  bearings,  connecting  rods,  wristplates,  dashpots,  reachrods,  valve  gears,  gover- 
nors, piping,  throttle  and  emergency  valves,  safety  stops,  fly-wheels,  oilers,  etc.  If 
there  is  any  trouble  with  these  parts,  the  book  gives  you  the  reasons  and  tells  how  to 
remedy  them. 

The  principal  considerations  in  the  building  of  foundations  are  given  with  the  size, 
area  and  weight  required  for  the  same,  also  the  setting  of  templets  and  lining  up,  and 
a  complete  account  of  the  erection  and  "breaking  in"  of  new  engines  in  the  language, 
of  the  man  on  the  job. 

Contains  special  chapters  on:  I.  Cylinders.  II.  Valves.  III.  Piping  and  Separa- 
tors. IV.  Throttle  and  Emergency  Valves.  V.  Pistons.  VI.  Frames.  VII.  Bear- 
ings, VIII.  Connecting  Rods.  IX.  Hockrods.  X.  Dashpots.  XI.  Governors. 
XII.  Releasing  Gears.  XIII.  Wristplates  and  Valve  Motions.  XIV.  Rodends  and 
Bonnets.  XV.  Oilers.  XVI.  Receivers.  XVII.  Foundations.  XVIII.  Erection. 
XIX.  Valve-Setting.     XX.  Operation.    284  pages.     276  illustrations.     Price  $2,50 

STEAM  HEATING  AND  VENTILATION 

PRACTICAL  STEAM,  HOT-WATER  HEATING  AND  VENTILATION.    By 
A.  G.  King. 

This  book  is  the  standard  and  latest  work  published  on  the  nubject  and  has  been  pre- 
pared for  the  use  of  all  engaged  in  the  business  of  steam,  hot- water  heating,  and  ventila- 
tion. It  is  an  original  and  exhaustive  work.  Tells  how  to  get  heating  contracts,  how 
to  install  heating  and  ventilating  apparatus,  the  best  business  methods  to  be  used, 
with  "Tricks  of  the  Trade"  for  shop  use.  Rules  and  data  for  estimating  radiation 
and  cost  and  such  tables  and  information  as  make  it  an  indispensable  work  for  every- 
one interested  in  steam,  hot- water  heating,  and  ventilation.  It  describes  all  the  principal 
systems  of  steam,  hot-water,  vacuum,  vapor,  and  vacuum-vapor  heating,  together 
with  the  new  accelerated  systems  of  hot-water  circulation,  including  chapters  on 
up-to-date  methods  of  ventilation  and  the  fan  or  blower  system  of  heating  and  ventila- 
tion. Containing  chapters  on:  I.  Introduction.  II.  Heat.  III.  Evolution  of 
artificial  heating  apparatus.  IV.  Boiler  surface  and  settings.  V.  The  chimney  flue. 
VI.  Pipe  and  fittings.  VII.  Valves,  various  kinds.  VIII.  Forms  of  radiating 
surfaces.  IX.  Locating  of  radiating  surfaces.  X.  Estimating  radiation.  XI.  Steam- 
heating  apparatus.  XII.  Exhaust-steam  heating.  XIII.  Hot-water  heating.  XIV. 
Pressure  systems  of  hot-water  work.  XV.  Hot-water  appliances.  XVI.  Greenhouse 
heating.  XVII.  Vacuum  vapor  and  vacuum  exhaust  heating.  XVIII.  Miscella- 
neous heating.  XIX.  Radiator  and  pipe  connections.  XX.  Ventilation.  XXI. 
Mechanical  ventilation  and  hot-blast  heating.  XXII.  Steam  appliances.  XXIII. 
District  heating.  XXIV.  Pipe  and  boiler  covering.  XXV.  Temperature  regulation 
and  heat  control.  XXVI.  Business  methods.  XXVII.  Miscellaneous.  XXVIII. 
Rules,  tables,  and  useful  information.  402  pages.  300  detailed  engravings.  Third 
Edition — Revised.    Price ••»#•••....     $3.56 

37 


CATALOGUE   OF   GOOD,  PRACTICAL  BOOKS 

p— — ~,~^""  — — — — — — 

BOO  PLAIN  ANSWERS  TO  DIRECT  QUESTIONS  ON  STEAM,  HOT-WATER, 
VAPOR  AND  VACUUM  HEATING  PRACTICE.         By  Alfred  G.  King. 

This  work,  just  off  the  press,  is  arranged  in  question  and  answer  form ;  it  is  intended  a3 
u  guide  and  text-book  for  the  younger,  inexperienced  fitter  and  as  a  reference  book  for 
all  fitters.  This  book  tells  "how"  and  also  tells  "why."  No  work  of  its  kind  has 
ever  been  published.  It  answers  all  the  questions  regarding  each  method  or  system 
that  would  be  asked  by  the  steam  fitter  or  heating  contractor,  and  may  be  used  as  a 
text  or  reference  book,  and  for  examination  questions  by  Trade  Schools  or  Steam 
^Fitters'  Associations.  Rules,  data,  tables  and  descriptive  methods  are  given,  to- 
gether with  much  other  detailed  information  of  daily  practical  use  to  those  engaged  in 
or  interested  in  the  various  methods  of  heating.  Valuable  to  those  preparing  for 
examinations.  Answers  every  question  asked  relating  to  modern  Steam,  Hot- Water, 
Vapor  and  Vacuum  Heating.  Among  the  contents  are:  The  Theory  and  Laws  of 
Heat.  Methods  of  Heating.  Chimneys  and  Flues.  Boilers  for  Heating.  Boiler 
Trimmings  and  Settings.  Radiation.  Steam  Heating.  Boiler,  Radiator  and  Pipe 
Connections  for  Steam  Heating.  Hot  Water  Heating.  The  Two-Pipe  Gravity 
System  of  Hot  Water  Heating.  The  Circuit  System  of  Hot  Water  Heating.  The 
Overhead  System  of  Hot  Water  Heating.  Boiler,  Radiator  and  Pipe  Connections  for 
Gravity  Systems  of  Hot  Water  Heating.  Accelerated  Hot  Water  Heating.  Ex- 
pansion Tank  Connections.  Domestic  Hot  Water  Heating.  Valves  and  Air  Valves. 
Vacuum  Vapor  and  Vacuo- Vapor  Heating.  Mechanical  Systems  of  Vacuum  Heating. 
^Non-Mechanical  Vacuum  Systems.  Vapor  Systems.  Atmospheric  and  Modulating 
Systems.  Heating  Greenhouses.  Information,  Rules  and  Tables.  214  pages,  127 
illustrations.     Octavo.     Cloth.     Price.     .     .     .     .     *     ,     .     .     ,     ,     .     $2.00 

STEEL 


BTEEL:  ITS  SELECTION,  ANNEALING,  HARDENING,  AND  TEMPERING. 
By  E.  R.  Markham. 

This  book  tells  how  to  select,  and  how  to  work,  temper,  harden,  and  anneal  steel  for 
everything  on  earth.  It  doesn't  tell  how  to  temper  one  class  of  tools  and  then  leave 
the  treatment  of  another  kind  of  tool  to  your  imagination  and  judgment,  but  it  gives 
careful  instructions  for  every  detail  of  every  tool,  whether  it  be  a  tap,  a  reamer  or  just 
a  screw-driver.  It  tells  about  the  tempering  of  small  watch  springs,  the  hardening  of 
cutlery,  and  the  annealing  of  dies.  In  fact,  there  isn't  a  thing  that  a  steel  worker 
would  want  to  know  that  isn't  included.  It  is  the  standard  book  on  selecting,  harden- 
ing, and  tempering  all  grades  of  steel.  Among  the  chapter  headings  might  be  mentioned 
the  following  subjects:  Introduction;  the  workman;  steel;  methods  of  heating; 
heating  tool  steel;  forging;  annealing;  hardening  baths;  baths  for  hardening;  harden- 
ing steel;  drawing  the  temper  after  hardening;  examples  of  hardening;  pack  harden- 
ing; case  hardening;  spring  tempering;  making  tools  of  machine  steel;  special  steels; 
steel  for  various  tools,  causes  of  trouble;  high  speed  steels,  etc.  400  pages.  Very 
fully  illustrated.     Fourth  Edition.     Price $3.00 

HARDENING,  TEMPERING,   ANNEALING,  AND  FORGING  OF  STEEL. 
INCLUDING  HEAT  TREATMENT  OF  MODERN  ALLOY  STEELS.     By 

J.   V.    WoQDWORTH. 

A  new  work  treating  in  a  clear,  concise  manner  all  modern  processes  for  the  heating, 
annealing,  forging,  welding,  hardening,  and  tempering  of  high  and  low  grade  steel, 
making  it  a  book  of  great  practical  value  to  the  metal- working  mechanic  in  general, 
with  special  directions  for  the  successful  hardening  and  tempering  of  all  steel  tools 
used  in  the  arts,  including  milling  cutters,  taps,  thread  dies,  reamers,  both  solid  and 
shell,  hollow  mills,  punches  and  dies,  and  all  kinds  of  sheet  metal  working  tools,  shear 
blades,  saws,  fine  cutlery,  and  metal  cutting  tools  of  all  description,  as  well  as  for  all 
implements  of  steel  both  large  and  small.  In  this  work  the  simplest  and  most  satis- 
factory hardening  and  tempering  processes  are  given. 

The  uses  to  which  the  leading  brands  of  steel  may  be  adapted  are  concisely  presented, 
and  their  treatment  for  working  under  different  conditions  explained,  also  the  special 
methods  for  the  hardening  and  tempering  of  special  brands. 

A  chapter  devoted  to  the  different  processes  for  case-hardening  is  also  included,  and 
special  reference  made  to  the  adaptation  of  machinery  steel  for  tools  of  various  kinds. 
5th  Edition,    321  pages.     201  illustrations,    >?rice $3.00 


38 


CATALOGUE   OF   GOOD,  PRACTICAL  BOOKS 


TRACTORS 

MODERN  GAS  TRACTOR:  ITS  CONSTRUCTION,  UTILITY,  OPERATION 
AND  REPAIR.     By  Victor  W.  Page. 

An  enlarged  and  revised  edition  that  treats  exclusively  on  the  design  and  construction 
of  farm  tractors  and  tractor  power  plants,  and  gives  complete  instructions  on  their 
care,  operation  and  repair.  All  types  and  sizes  of  gasoline,  kerosene  and  oil  tractors 
are  described,  and  every  phase  of  traction  engineering  practice  fully  covered.  In- 
valuable to  all  desiring  reliable  information  on  gas  motor  propelled  traction  engines? 
and  their  use.  All  new  1921  types  of  tractors  are  described  and  complete  instructions 
are  given  for  their  use  on  the  farm.  The  chapter  on  engine  repairing  has  been  greatly 
enlarged  and  complete  and  detailed  instructions  are  now  given  for  repairing  weh- 
known  and  widely  used  tractor  power  plants,  numerous  new  forms  of  which  are 
described.  Valuable  information  compiled  by  Government  experts  on  laying  out- 
fields for  tractor  plowing  and  numerous  practical  suggestions  for  hitches  so  all  types; 
of  agricultural  machinery  can  be  operated  by  tractors,  are  outlined.  The  chapter- 
on  tractor  construction  and  upkeep  has  been  more  than  doubled  in  size.  Over  10O 
new  illustrations  have  been  added  and  the  book  greatly  enlarged.  Full  instructions: 
are  now  given  for  using  kerosene  and  distillate  as  fuel.  The  1921  edition  is  38>  per- 
cent larger  than  the  second  edition  and  is  more  than  ever  the  acknowledged  authemiy' 
on  farm  tractors  and  their  many  uses.  5  \i  x  1XA  inches.  Cloth,  nearly  700  pages*- 
and  about  300  illustrations,  3  folding  plates.     Price _•     .     $3.00 

WELDING 

MODERN  WELDING  METHODS.     By  Victor  W.  Page1. 

One  of  the  most  instructive  books  on  all  methods  of  joining  metals  yet  published  for 
the  mechanic  and  practical  man.  It  considers  in  detail  oxy-acetylene  welding,  the 
Thermit  process  and  all  classes  of  electric  arc  and  resistance  welding.  It  shows  all 
the  apparatus  needed  and  how  to  use  it.  It  considers  the  production  of  welding  gases, 
construction  and  operation  of  welding  and  cutting  torches  of  all  kinds.  It  details 
the  latest  approved  methods  of  preparing  work  for  welding.  All  forms  of  gas  and 
electric  welding  machines  are  described  and  complete  instructions  are  given  for 
installing  electric  spot  and  butt  welders.  Cost  data  are  given  and  all  methods  of 
doing  the  work  economically  are  described.  It  includes  instructions  for  forge  and 
dip  brazing  and  manufacture  of  hard  solders  and  spelters.  It  shows  and  explains 
soft  soldering  processes  and  tells  how  to  make  solders  for  any  use.  Complete  instruc- 
tions are  given  for  soldering  aluminum  and  authoritative  formulas  for  aluminum  solders 
are  included.     292   pages.     200   illustrations.     1921    edition.     Price     .      .    '$3.00 

AUTOMOBILE  WELDING  WITH  THE   OXY-ACETYLENE  FLAME.      By 

M.  Keith  Dunham. 

Explains  in  a  simple  manner  apparatus  to  be  used,  its  care,  and  how  to  construct 
necessary  shop  equipment.  Proceeds  then  to  the  actual  welding  of  all  automobile 
parts,  in  a  manner  understandable  by  everyone.  Gives  principles  never  to  be  for- 
gotten. This  book  is  of  utmost  value,  since  the  perplexing  problems  arising  when 
metal  is  heated  to  a  melting  point  are  fully  explained  and  the  proper  methods  to 
overcome  them  shown.    167  pages.    Fully  illustrated.    Price .    ,     ♦     ,     ,     $1,50 


39 


MTC  ,  a. .DATE  DUE 

J-73U 

1 

SEP  ~l 

1993 

JAM  \ 

\  2  2004 

UNIVERSITY  PRODUCTS,  INC.    #859-5503 

142757 


BOSTON  COLLEGE 

Pill  lill  I  llllll  III! 


3  9031   01460939  0 


i  ^^-msMBKmtamm 


' 


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